Publication number | US6831431 B1 |

Publication type | Grant |

Application number | US 10/019,849 |

PCT number | PCT/EP2000/007622 |

Publication date | Dec 14, 2004 |

Filing date | Aug 5, 2000 |

Priority date | Sep 22, 1999 |

Fee status | Lapsed |

Also published as | DE10041027A1, DE50011298D1, EP1214602A1, EP1214602B1, EP1214602B8, WO2001022095A1, WO2001022095A8 |

Publication number | 019849, 10019849, PCT/2000/7622, PCT/EP/0/007622, PCT/EP/0/07622, PCT/EP/2000/007622, PCT/EP/2000/07622, PCT/EP0/007622, PCT/EP0/07622, PCT/EP0007622, PCT/EP007622, PCT/EP2000/007622, PCT/EP2000/07622, PCT/EP2000007622, PCT/EP200007622, US 6831431 B1, US 6831431B1, US-B1-6831431, US6831431 B1, US6831431B1 |

Inventors | Roland Dieterle, Alexander Hahn, Hermann Rappenecker |

Original Assignee | Papst-Motoren Gmbh & Co. Kg |

Export Citation | BiBTeX, EndNote, RefMan |

Patent Citations (36), Non-Patent Citations (5), Referenced by (31), Classifications (17), Legal Events (10) | |

External Links: USPTO, USPTO Assignment, Espacenet | |

US 6831431 B1

Abstract

The invention concerns a method for regulating the rotation speed, of a motor with which a digital rotation speed controller is associated and which, during operation, furnishes an actual-value signal for the rotation speed in the form of a rotation speed frequency signal, toward a target rotation speed setpoint defined in the form of a setpoint frequency signal, having the following steps: in a first time segment, a first numerical frequency value that characterizes the rotation speed of the motor is ascertained from the rotation speed frequency signal; in a second time segment that is substantially simultaneous with the first time segment, a second numerical frequency value that characterizes the frequency of the setpoint frequency signal is ascertained from the setpoint frequency signal; by means of the first and second numerical frequency values, the rotation speed of the motor is regulated in the digital rotation speed controller to a rotation speed that is associated with the setpoint frequency signal according to a predetermined mathematical relationship.

Claims(56)

1. A method of controlling the actual value of the rotation frequency of a motor having a digital rotation frequency controller associated therewith, so that said motor will run at a target rotation frequency having a predetermined mathematical relationship to a target frequency supplied to said controller,

comprising executing repeatedly, in an arbitrary sequence, the two steps of:

in a first time segment, having a length determined by events of the rotation frequency, obtaining, from the actual value of the rotation frequency signal, a first numerical frequency value characterizing the rotation frequency of the motor;

in a second time segment, having a length determined by events of the target frequency and overlapping the first time segment, obtaining, from said target frequency, a second numerical frequency value characterizing the frequency thereof;

followed by the step of, by means of the first and second numerical frequency values, controlling, using the digital speed controller, the rotation frequency of the motor toward a said target rotation frequency having a predetermined mathematical relationship to the target frequency.

2. The method according to claim 1 , further comprising,

in order to obtain said first and second numerical values, measuring the length of the first time segment and the length of the second time segment overlapping the first time segment.

3. The method according to claim 2 , wherein

the measuring of the first time segment and the measuring of the second time segment comprise measuring a time interval between edges of the respective frequency signal.

4. The method according to claim 2 , further comprising

using an identical time standard for time measurement for obtaining the first numerical value and for time measurement for obtaining the second numerical value.

5. The method according to claim 1 , of determining a numerical value for the frequency of a frequency signal which, at a constant frequency, comprises a fixed number of events per unit time, said events being selected from the group consisting of signal pulses and signal edges,

comprising the steps of:

a) at a first predetermined instant, initiating measurement of a frequency datum;

b) ascertaining a second instant, at which an event of the frequency signal subsequent to the first predetermined instant occurs;

c) counting the number of events of the frequency signal subsequent to the second instant;

d) at a third predetermined instant, initiating termination of measurement of the frequency datum;

e) ascertaining a fourth instant, at which an event of the frequency signal subsequent to the third predetermined instant occurs; and

f) calculating the numerical value from the time interval between the second instant and fourth instant, and from the number of events of the frequency signal counted between said instants.

6. The method according to claim 5 , wherein

said step of ascertaining the fourth instant comprises using the next event of the frequency signal as the event subsequent to the third predetermined instant.

7. The method according to claim 5 , further comprising, for ascertaining the fourth instant, selecting, as the event subsequent to the third predetermined instant, that next event of the frequency signal at which the number of events since the second instant is equal to a product a*N, where a and N are whole numbers, of which one is equal to at least 1 and the other is equal to at least 2.

8. The method according to claim 7 , wherein, in the case of a rotation speed frequency signal (f), the number N corresponds to a fixed number of events per revolution of the rotor.

9. The method according to claim 5 , further comprising continuously measuring said first and second numerical values.

10. The method according to claim 9 , wherein the first predetermined instants of successive measurements have defined time offsets (T_A); and

wherein the third predetermined instants each have a substantially constant time offset from the associated first predetermined instants.

11. The method according to claim 9 , wherein the third predetermined instant of a first measurement corresponds to the first predetermined instant of a second measurement subsequent thereto.

12. The method according to claim 11 , wherein the fourth instant of a first measurement corresponds to the second instant of a second measurement subsequent thereto.

13. The method according to claim 5 , further comprising

calculating said numerical value by dividing the number (N) of events of the frequency signal between the second and fourth instants by the time interval (Δt) between said second and fourth instants.

14. The method according to claim 13 , further comprising the step of multiplying the numerical value by multiplication with a constant factor.

15. The method according to claim 14 , further comprising selecting the constant factor such that the numerical value substantially corresponds to a conventional rotation speed indication.

16. The method according to claim 13 , further comprising dividing a numerator proportional to the number of pulses between the second and fourth instants by a denominator proportional to the time interval between the second and fourth instants, obtaining, as a result, an integral frequency datum and a remainder; and

using the remainder by adding it to the numerator of the subsequent measurement.

17. A method of obtaining a numerical value concerning the rotation speed of a rotor, according to claim 5 , further comprising the steps of:

a) during a first measurement period (T_M**1**), counting the number (N) of events of the rotation speed signal (f);

b) measuring the time duration (Δt) of the first measurement period (T_M**1**);

c) performing an integral division (“div”) in which the number of events during the first measurement period (T_M**1**) is the numerator and the time duration of the first measurement period (T_M**1**) is the denominator, thereby obtaining a first integral rotation speed numerical value and a remainder (S**372**; S**472**); and

d) during a subsequent measurement, adding said remainder (REM_n_OLD; REM_n_s_OLD) to the numerator in a subsequent integral division forming part of said subsequent measurement.

18. The method according to claim 17 , wherein the number (N) of events prior to the integral division (S**372**; S**472**) is multiplied by a constant factor that is greater than 1, in order to obtain a result of the integral division that is large in relation to the remainder (REM_n; REM_n_s).

19. The method according to claim 18 , wherein the constant factor is a power of two (2^{h}; 2^{h} ^{ — } ^{s}).

20. The method according to claim 19 , wherein the exponent (h; h_s) of the power of two is an adjustable variable.

21. An apparatus comprising

a motor having a rotor,

a sensor (**61**) which furnishes a motor frequency signal (f) having a frequency defined by the rotation speed of said rotor and providing a defined number of events for each revolution of the rotor,

a digital rotation speed controller associated with said motor for controlling the rotation frequency thereof;

first input means for supplying the motor frequency signal to said digital controller;

second input means for supplying a target frequency to said digital controller;

said digital controller having a program associated therewith for controlling said rotation speed toward a target rotation speed having a predetermined mathematical relationship to said target frequency, said program being adapted for repeatedly executing, in an arbitrary sequence, the two steps of

in a first time segment, having a length determined by events of the motor frequency signal, obtaining from said signal a first numerical value characterizing the actual rotation speed of the motor,

in a second time segment, having a length determined by events of the target frequency and overlapping the first time segment, obtaining, from said target frequency, a second numerical value characterizing the target frequency;

followed by the step of, by means of said first and second numerical values, controlling, using the digital speed controller, the rotation speed of the motor toward said target rotation speed having a predetermined mathematical relationship to said target frequency.

22. An apparatus according to claim 21 which performs the steps of:

a) initiating measurement of the first numerical value in response to a first control signal;

b) ascertaining a first instant, at which an event of the rotation speed signal (f) subsequent to the first control signal occurs;

c) counting the number of events of the rotation speed signal (f) subsequent to said first instant;

d) initiating termination of measurement of the first numerical value in response to a second control signal;

e) ascertaining a second instant, at which an event of the rotation speed signal (f) subsequent to the second control signal occurs;

f) calculating said first numerical value from the time interval (Δt_MEAS_f(**175**-**177**)) between the first instant (**161**) and the second instant (**163**), and from the number (N) of events of the rotation speed signal (f) between said two instants; and

g) using the thus-calculated numerical value in controlling rotation speed.

23. The apparatus according to claim 22 , wherein the source of the control signals comprises a timer (TIMERø).

24. The apparatus according to claim 23 , wherein the timer (TIMERø) is configured so as to trigger interrupt operations (TIMERø Interrupt) as control signals.

25. The apparatus according to claim 22 , further comprising a timer (TIMER**1**) for measuring time elapsed between the first and second instants.

26. The apparatus according to claim 25 , wherein the timer (TIMER**1**) for measuring the time between the first and second instants is a ring counter.

27. The apparatus according to claim 26 , wherein

the ring counter (TIMER**1**), in operation, counts continuously, and the end of a completed measurement is substantially contemporaneous with the beginning of a new measurement.

28. The apparatus according to claim 21 , wherein a signal from an electronically commutated motor serves as the motor frequency signal (f).

29. The apparatus according to claim 21 , wherein a counter (INT_CNT_f) for events of the rotation speed motor frequency signal (f) is provided.

30. An apparatus according to claim 21 , wherein said apparatus responds to application of a target value frequency of zero by regulating rotation speed to zero.

31. The apparatus according to claim 21 , wherein a single timer (TIMER**0**) is provided for both measuring the length (Δt_MEAS_f) of the first time segment and measuring the length (Δt_MEAS_f_s) of the second time segment.

32. A method of ascertaining a plurality of numerical values characterizing the frequencies of a plurality of sensed signals (f; f_s), said signals each comprising a sequence of events selected from the group consisting of signal pulses and signal edges, comprising the steps of:

a) for at least two of said signals, initiating measurement of their associated numerical value at a first predetermined instant;

b) for each of said signals, ascertaining a second instant, at which a frequency datum of said signal subsequent to the first predetermined instant occurs;

c) separately sensing the number of events of each of said signals subsequent to the second instant;

d) at a third predetermined instant, initiating termination of measurement of said signals;

e) for each of said signals, separately ascertaining a fourth instant, at which a frequency datum of said signal subsequent to the third predetermined instant occurs;

f) from the time interval between the respective second instant and the respective fourth instant, and from the number of frequency data of the respective signal between said respective instants, calculating, for each of said signals, the numerical value characterizing its frequency.

33. The method according to claim 32 , further comprising, in order to ascertain the respective fourth instant,

selecting the next frequency datum of the respective signal as the frequency datum subsequent to the third predetermined instant.

34. The method according to claim 32 , further comprising, in order to ascertain the respective fourth instant, selecting, as the frequency datum subsequent to the third predetermined instant, that next frequency datum of the respective signal at which the number of frequency data since the second instant corresponds to an integral multiple of a whole number from the series 2, 3, 4, . . . .

35. The method according to claim 32 , wherein frequency measurements are performed continuously and the third predetermined instants each have a substantially constant time offset (T_A) from the associated first predetermined instants.

36. The method according to claim 35 , wherein the third predetermined instant of the measurement of a signal corresponds to the first predetermined instant of a subsequent measurement.

37. The method according to claim 35 , wherein

the fourth instant of a measurement corresponds to the second instant of a subsequent measurement of the same signal.

38. The method according to claim 32 , wherein

the first predetermined instants, for initiating measurement of the plurality of signals, are substantially identical to each other.

39. The method according to claim 32 , wherein the third predetermined instants, for initiating termination of the measurement of the plurality of signals, are substantially identical to each other.

40. A method of controlling the actual value of the rotation frequency of a motor having a digital rotation frequency controller associated therewith so that said motor will run at a target rotation frequency having a predetermined mathematical relationship to a target frequency supplied to said controller, comprising:

proving a rotation frequency signal and a target frequency signal;

using an identical time standard, repeatedly executing, in an arbitrary sequence, the following two steps:

measuring the length of a first time segment by measuring a time interval between edges of the rotation frequency signal and obtaining, from the rotation frequency signal and the measured length of the first time segment, a first numerical value characterizing the actual rotation frequency of the motor;

measuring the length of a second time segment by measuring a time interval between edges of the target frequency signal and obtaining, from the target frequency signal and the measured length of the second time segment, a second numerical value characterizing the frequency of the target frequency signal;

followed by the step of:

by means of said first and second numerical values, controlling, using the digital frequency controller, the rotation frequency of the motor toward said target rotation frequency having a predetermined mathematical relationship to said supplied target frequency.

41. The method according to claim 39 , of determining a numerical value for the frequency of a frequency signal which, at a constant frequency, comprises a fixed number of events per unit time, said events being selected from the group consisting of signal pulses and signal edges,

comprising the steps of:

a) at a first predetermined instant, initiating measurement of a frequency datum;

b) ascertaining a second instant, at which an event of the frequency signal subsequent to the first predetermined instant occurs;

c) counting the number of events of the frequency signal subsequent to the second instant;

d) at a third predetermined instant, initiating termination of measurement of the frequency datum;

e) ascertaining a fourth instant, at which an event of the frequency signal subsequent to the third predetermined instant occurs; and

f) calculating the numerical value from the time interval between the second instant and fourth instant, and from the number of events of the frequency signal counted between said instants.

42. The method according to claim 41 , wherein

said step of ascertaining the fourth instant comprises using the next event of the frequency signal as the event subsequent to the third predetermined instant.

43. The method according to claim 41 , further comprising, for ascertaining the fourth instant, selecting, as the event subsequent to the third predetermined instant, that next event of the frequency signal at which the number of events since the second instant is equal to a product a*N, where a and N are whole numbers, of which one is equal to at least 1 and the other is equal to at least 2.

44. The method according to claim 43 , wherein, in the case of a rotation speed frequency signal (f), the number N corresponds to a fixed number of events per revolution of the rotor.

45. The method according to claim 41 , further comprising continuously measuring said first and second numerical values.

46. The method according to claim 45 , wherein the first predetermined instants of successive measurements have defined time offsets (T_A); and

wherein the third predetermined instants each have a substantially constant time offset from the associated first predetermined instants.

47. The method according to claim 46 , wherein the third predetermined instant of a first measurement corresponds to the first predetermined instant of a second measurement subsequent thereto.

48. The method according to claim 47 , wherein the fourth instant of a first measurement corresponds to the second instant of a second measurement subsequent thereto.

49. The method according to claim 41 , further comprising

calculating said numerical value by dividing the number (N) of events of the frequency signal between the second and fourth instants by the time interval (Δt) between said second and fourth instants.

50. The method according to claim 49 , further comprising the step of multiplying the rotation speed datum by multiplication with a constant factor.

51. The method according to claim 50 , further comprising selecting the constant factor such that the rotation speed datum substantially corresponds to a conventional rotation speed indication.

52. The method according to claim 49 , further comprising dividing a numerator proportional to the number of pulses between the second and fourth instants by a denominator proportional to the time interval between the second and fourth instants, obtaining, as a result, an integral frequency datum and a remainder; and

using the remainder by adding it to the numerator of the subsequent measurement.

53. The method of obtaining a numerical value concerning the rotation speed of a rotor, according to claim 41 , further comprising the steps of:

a) during a first measurement period (T_M**1**), counting the number (N) of events of the rotation speed signal (f);

b) measuring the time duration (Δt) of the first measurement period (T_M**1**);

c) performing an integral division (“div”) in which the number of events during the first measurement period (T_M**1**) is the numerator and the time duration of the first measurement period (T_M**1**) is the denominator, thereby obtaining a first integral rotation speed numerical value and a remainder (S**372**; S**472**); and

d) during a subsequent measurement, adding said remainder (REM_n_OLD; REM_n_s_OLD) to the numerator in a subsequent integral division forming part of said subsequent measurement.

54. The method according to claim 53 , wherein the number (N) of events prior to the integral division (S**372**; S**472**) is multiplied by a constant factor that is greater than 1, in order to obtain a result of the integral division that is large in relation to the remainder (REM_n; REM_n_s).

55. The method according to claim 54 , wherein the constant factor is a power of two (2^{h}; 2^{h} ^{ — } ^{s}).

56. The method according to claim 55 , wherein the exponent (h; h_s) of the power of two is an adjustable variable.

Description

The invention concerns a method for regulating the rotation speed of a motor, and a motor for carrying out such a method.

Digital systems for sensing and regulating the rotation speed of a rotating object (“rotor”) are based on the fact that such a rotor generates one or more signals, e.g. needle pulses, pulse edges, or the like, at each revolution. These signals are referred to hereinafter as “events.” Measurement of a rotation speed is based on measuring the time offset l between such “events” or counting the number of such “events” that occur per unit time. In a regulation process, this rotation speed information is used to keep the rotation speed of a motor at a defined value. A “motor” (prime mover) is understood here to be any kind of motor, e.g. an internal combustion engine, electric motor, pneumatically or hydraulically operating is motor, turbine, etc. The invention is preferably applied to regulating the rotation speed of electric motors.

Since the number of such “events” per unit time increases with increasing rotation speed, processing them in a digital system requires more calculation time as the rotation speed becomes greater, so that the calculation time available for other processes decreases.

It is an object of the invention to make available a new method for regulating the rotation speed of a motor, and a motor for carrying out such a method.

According to a first aspect of the invention, this object is achieved by [a method according to claim **1**.] calculating a first numerical frequency value representing actual rotation speed and a second numerical frequency value representing a target rotation speed, and processing these values in a digital motor controller in order to regulate the rotation speed toward the target value. Because two digital frequency values are calculated, it is possible to subject one or even both of said frequency values to a mathematical transformation and thus, by means of the digital controller, to create a desired relationship between the first and the second frequency value. Often one of the digital frequency values, or even both, will be multiplied by a constant factor, which in digital terms is often possible by decimal-point shifting and easily makes possible an electronic gearbox; other relationships are also conceivable, however, for example an exponential function or any other mathematical function in accordance with the requirements of the particular drive system task.

A particularly advantageous embodiment of the invention is [the subject matter of claim **5**] to define a series of four instants which span multiple “events” of the frequency signal, and to use a count of events between the second and fourth instants to calculate the frequency. Because multiple “events” of the frequency signal can be sensed with one measurement, an averaging takes place upon measurement of the frequency information. This is because if the frequency is ascertained by means of a plurality of short measurements, it is often necessary to determine a moving average from multiple measured values by calculation. With the invention, on the other hand, an average is obtained without additional calculation, thus additionally relieving the load on, for example, a microprocessor or microcontroller, both hereinafter abbreviated as μC. And despite the approximate definition of a measurement duration by means of the predetermined instants, in the method the actual measurement takes place exactly between two events of the frequency signal. This has proven particularly advantageous because measurement exactly between two defined events of a frequency signal makes possible particularly high accuracy.

Another advantageous development of the invention is [the subject matter of claim **8**] to count “events” which happen a fixed number of times per revolution of the rotor. The result of this is that, upon measurement of a rotation speed datum in the context of a rotor having a fixed number of “events” per rotor revolution, measurement always occurs between such “events” which are associated with the same rotational position of the rotor, i.e. complete revolutions are measured. This is of interest in particular for rotors which comprise multiple “marks” for generating the rotor position signal, which marks do not have identical angular spacings. The result of the development, [according to claim **8**] using such a fixed number of events per revolution, is thus that measurement always occurs at the same point on the rotor, so that the exactness of the angular spacings is immaterial. High measurement accuracy results therefrom. “Marks” are understood here also to mean invisible marks, e.g. a pattern in the magnetization of a permanent-magnet rotor.

Another advantageous development of the invention is [the subject matter of claim **12**] to have the fourth instant of a first measurement correspond to the second instant of a second measurement. A frequency datum is measured continuously by means of such a method, since the next measurement seamlessly follows the present measurement. In the vicinity of each predetermined instant, a present measurement is ended and a new measurement is begun. If the predetermined instants each occur after a time T_A, a measurement then takes place, on average, after a time T_A in each case. Processing of the measurements, for example in a μC, thus takes place at regular intervals that are independent of the rotation speed. The μC is thereby under a uniform load for these tasks at all rotation speeds. Since in this case there is no pause between the individual measurements, this method is particularly suitable if each individual revolution of the rotor must be taken into account for measurement or regulation, for example as is necessary in motors with high-accuracy controllers or in stepping motors.

The invention furthermore concerns a method according to [claim **16**] which the remainder from a first measurement is used in the calculation for a following measurement. The result of taking into account the remainder in the subsequent measurement is that, in the context of a calculation of the frequency information by division, no frequency information is lost due to rounding. This results very advantageously in an increase in the accuracy of the measurement, and is very advantageous in the context of complex control processes that require high precision. Two or more motors can thus run synchronously with one another by the fact that the same frequency signal is delivered to all said motors, i.e. without a higher-level controller. Systems having higher-level controllers are relatively slow, have long initial transients, and are susceptible to oscillations especially at low rotation speeds. A method according to the invention, on the other hand, operates quickly because only a few program steps are needed to take the remainder into account. A method according to the present invention can also easily be switched over to different parameters, e.g. to a different “gearbox factor,” different control parameters, etc.

The preferred use of a ring counter [according to claim **25**] to measure the time between first and second instants, and the development [according to claim **26**] in which the ring counter counts continuously, have the advantage that the termination of one measurement and the start of the subsequent measurement are simultaneous because the ring counter is always running, so that no errors can occur due to measurement delay; and any delays (resulting, for example, from the simultaneous occurrence of two interrupts) are subsequently immediately compensated for, since the time of the subsequent measurement cycle automatically becomes slightly too short.

This makes possible seamless sensing of the rotation speed and an average rotation speed sensing error that is close to zero, since not a single bit is lost during measurement. A ring counter of this kind usually has a so-called pre-scaler with which it is possible to set the frequency at which said counter counts. By setting this function on a bit-by-bit basis, the ring counter can be clocked at various fixed multiples of the quartz oscillator frequency of the μC. The counting frequency and resolution of the ring counter can thereby be optimized for the application. This setting can be accomplished by way of a parameter that is stored in the motor in a nonvolatile memory. The resolution of the ring counter can thereby be optimized for different rotation speed ranges using different parameters.

Further details and advantageous developments of the invention are evident from the exemplary embodiments—which are in no way to be understood as a limitation of the invention—that are described below and depicted in the drawings, and from the other dependent claims. In the drawings:

FIG. 1 is a schematic depiction of an arrangement according to the present invention for regulating the rotation speed of a motor to a value that is defined from outside by a frequency signal f_s;

FIG. 2 shows the pin assignment of a μC used in the exemplary embodiment, in this case a Microchip PIC 16C72;

FIG. 3 is a schematic circuit diagram of a preferred embodiment of a motor according to the invention, in this case with one electric motor **32**;

FIG. 4 shows a frequency signal f before and after signal processing;

FIG. 5 is a schematic depiction to explain a detail of FIG. 3;

FIG. 6 is a schematic depiction to explain a detail of FIG. 3;

FIG. 7 is a schematized depiction of a control arrangement that makes possible an “electronic gearbox”;

FIG. 8 is a flow chart with an overview of the entire program, here in the form of a so-called function manager;

FIG. 9 shows a function register that is used in conjunction with FIG. 8;

FIG. 10 is a state diagram for a preferred measurement method for measuring a frequency signal;

FIG. 11 is a diagram showing, by way of example, the quasi-simultaneous measurement of a setpoint frequency f_s and an actual frequency f;

FIG. 12 is a flow chart for a function TIMER**0** Interrupt;

FIG. 13 is a flow chart for a function Hall Interrupt;

FIG. 14 is a flow chart for a function f_s Interrupt;

FIG. 15 is a flow chart for a function CALC_n for calculating the instantaneous value of the rotation speed (actual rotation speed);

FIG. 16 is a flow chart for a function CALC_n_s for calculating a rotation speed setpoint n_s:

FIG. 17 is a flow chart for a function RGL_ON which determines when the RGL function of FIG. 13 is started;

FIG. 18 is a flow chart for the function RGL for regulating the rotation speed; this function makes possible an “electronic gearbox”;

FIG. 19 is a state diagram for the general execution of the control process;

FIG. 20 is a state diagram for a controller in which the rotation speed setpoint n_s=0 can also be set;

FIG. 21 is a flow chart for a function RGL_ON**2** which is adapted to the state diagram of FIG. 20;

FIG. 22 is a schematic depiction to explain a preferred measurement method in the case of a rotor having a single mark **290**;

FIG. 23 is a schematic depiction of a rotation speed calculation function;

FIG. 24 is a schematic depiction of a preferred manner of measurement in the case of a rotor having two marks **291** and **292**;

FIG. 25 is a schematic depiction of a measurement analogous to FIG. 24 in which an interference signal S occurs, for explanation of the operations occurring in that context;

FIG. 26 is a depiction with three electric motors **181**, **183**, **185** which have different numbers of rotor poles and which here are regulated by the same setpoint frequency signal f_s to the same rotation speed n;

FIG. 27 is a highly schematized depiction of a copier that has three drive motors M**1**, M**2**, and M**3**, which all receive the same control signal f_s for their rotation speed and which, thanks to the gearbox function, run at different rotation speeds that are at defined numerical ratios to f_s;

FIG. 28 is a schematic depiction with three motors M**1**, M**2**, M**3**, of which M**1** is the master motor that supplies to the two other motors M**2** and M**3** a signal TACHO that constitutes an indication of the rotation speed of M**1** and that regulates the rotation speeds of the other two motors in such a way that said rotation speeds are always at a defined ratio to the rotation speed of motor M**1**; and

FIG. 29 is a schematic depiction analogous to FIG. 6 which shows the commutation of an electronically commutated motor **32**″ by μC **23**.

Identical or identically operating parts are labeled hereinafter with the same reference characters and are usually described only once.

FIG. 1 is a block diagram of an arrangement **18** according to the present invention having one motor M. The latter is depicted here as electric motor **32**, but could be any other motor whose rotation speed can be modified by means of an actuating signal, e.g. in the case of an internal combustion engine by means of a change in fuel delivery, in the case of a steam turbine by way of a change in steam delivery, etc.

Electric motor **32** is connected at a terminal **33** to a positive operating voltage +U_B and at another terminal **34** to ground GND. The energization of motor **32** is controlled by means of a control output SW **27** in order to regulate its rotation speed. A rotor position signal of motor **32** is delivered as frequency f **29** to a microprocessor or microcontroller, hereinafter called μC **23**. A target or setpoint frequency f_s **25** is also delivered to μC **23**, e.g. from a frequency generator **20** that can also be, for example, another electric motor, as will be described below with reference to FIG. **28**. In FIG. 28, motor M**1** defines, by way of its output signal, the rotation speed of motors M**2** and M**3**, i.e. the latter can, for example, run at the same rotation speed as motor M**1**, or at different rotation speeds that are at a desired rotation speed ratio to the rotation speed of motor M**1**.

Since μC **23** is small, it can be combined together with motor **32** into module **18**, namely into a motor unit **18** with an “electronic gearbox.” This is possible even for electric motors that are referred to, according to the common definition, as miniature or subminiature motors.

Implemented in μC is a rotation speed controller n-CTRL **35** that regulates control output SW **27** so as to create, between setpoint frequency f_s and actual frequency f, a fixed ratio that can be described as follows:

*f* _{—} *s/f=y/z* (1)

where y and z are whole numbers. This is therefore the aforementioned “electronic gearbox.”

This makes it possible, for example, synchronously to control one motor **181** having a two-pole rotor R_**2**, one motor **183** having a four-pole rotor R_**4**, and one motor **185** having a six-pole rotor R_**6** using a single setpoint frequency f_s, as depicted in FIG. 26, so that, for example, all three motors rotate at the same desired rotation speed n that is at a specific ratio to f_s.

For that purpose, for example,

*f* _{—} *s/f*_**2**=20/2,

*f* _{—} *s/f*_**4**=20/4, and

*f* _{—} *s/f*_**6**=20/6

are set, f_**2** being the actual frequency of two-pole rotor R_**2**, f_**4** the actual frequency of four-pole rotor R_**4**, and f_**6** the actual frequency of rotor R_**6**. The depiction in FIG. 26 is based on the assumption that a Hall generator controlled by the magnetic field of the rotor in question is used therein, in the usual way, to sense the rotor position (cf. FIG. **11**C and FIG. **29**). The ratios result from the fact that with two-pole rotor R_**2**, two changes in the Hall signal (“Hall changes”) take place per revolution, while with four-pole rotor R_**4** four Hall changes take place per revolution, and with six-pole rotor R_**6**, six Hall changes occur per revolution.

An arrangement of this kind is of interest principally for devices having several motors, in which the motors must be at a fixed rotation speed ratio to one another.

FIG. 2 shows the terminals of a μC **23**. In this exemplary embodiment, a model PIC 16C72 microcontroller of the MICROCHIP company is used. This is an 8-bit processor. It contains a 16-bit timer and an 8-bit timer, two Pulse Width Modulation (PWM) registers, and multiple interrupt functions. This processor of course represents only one example, but it has proven to be the best mode for the embodiment described.

μC **23** has, among others, terminals MCLR **37**, VSS **38**, CLKIN **39**, CLKOUT **40**, C**1** **41**, B**5** **42**, B**4** **43**, VDD **44**, VSS **45**, SDA **46**, and SCL **47**.

FIG. 3 shows a greatly schematized circuit diagram of a preferred arrangement with one electric motor **32**.

The terminals of μC **23** are depicted in FIG. 2, and the corresponding reference characters are used again. Terminal MCLR **37** is connected via a resistor **71** to a positive voltage +5V. Terminals CLKIN **39** and CLKOUT **40** are connected to a quartz oscillator **75**. Terminal VDD **44** is connected to +5V and terminal VSS **45** to ground GND, and the two terminals are connected to one another through a capacitor **77**. μC **23** has two timers TIMER**0** and TIMER**1** that are depicted schematically in FIG. **1**.

Setpoint frequency f_s passes via a line **25** to a filter FILT_s **51**, and from there via a line **53** to terminal B**4**.

Actual frequency f (corresponding to the rotation speed of motor **32**), which is sensed by a rotor position sensor **61**, passes via a line **29** to a filter FILT **57**, and from there via line **59** to terminal B**5** **42** of μC **23**.

An EEPROM **80** has terminals SDA **81**, SCL **83**, VDD **89**, WP **95**, VSS **99**, Al **100**, A**2** **101**, and A**3** **103**. EEPROM stands for Electrically Erasable Programmable Read-Only Memory.

Terminal SDA **46** of μC **23** is connected via a line **78** to terminal SDA **81** of EEPROM **80** and to an external terminal **105**.

Terminal SCL **47** of μC **23** is connected via a line **79** to terminal SCL **83** of EEPROM **80** and to an external terminal **107**. Terminals **105**, **107** provide connection to a communication bus B.

Terminals VSS **99**, A**1** **100**, A**2** **101**, and A**3** **103** of EEPROM **80** are connected to ground GND. Terminal WP **95** is connected via a resistor **97** to ground GND. Terminals SDA **81** and SCL **83** are connected via pull-up resistors **85** and **87**, respectively, to +5V. Terminal VDD **89** is connected via a line **91** to +**5**V and via a capacitor **93** to ground GND.

Motor **32** has an adjusting member SG **63** which influences the magnitude of a current i flowing through motor **32**.

Adjusting member **63** is connected via a line **33** to voltage +U_B, and a control output SW is delivered via a line **27** from terminal C**1** of μC **23** to adjusting member SG **63** in order to influence the magnitude of current i. A resistor **65** is located between terminal C**1** of μC **23** and line **27**, and node **66** is connected via a capacitor **67** to ground GND. Resistor **65** and capacitor **67** together form an integration member whose operation will be explained below with reference to FIG. **5**.

μC **23** receives its operating voltage through terminal VDD **44** at +5V and VSS **45** at ground GND. The supply voltage is protected from voltage spikes and dips by a filter capacitor **77**. The clock frequency of μC **23** is generated by means of oscillator **75** connected to terminals CLKIN **39** and CLKOUT **40**.

Terminals SDA **46** and SCL **47** of μC **23** serve for serial transfer of data between μC **23** and EEPROM **80** (terminals SDA **81** and SCL **83**, respectively, thereon), and to external terminals **105** and **107**, respectively, that are connected, for example, to external bus B.

EEPROM **80** receives its voltage via terminal VDD **89**, which is connected via line **91** to +5V and is additionally protected by a capacitor **93** from voltage spikes; and via terminal VSS **99** that is connected to ground GND. Write-protect terminal WP **95** is taken to ground GND via resistor **97**, so that in this exemplary embodiment EEPROM **80** cannot be written to. For the same reason, terminals A**1** **100**, A**2** **101**, and A**3** **103**, which provide address coding, are also connected to ground GND. In this exemplary embodiment, the parameters are permanently written in EEPROM **80**. Variants having an EEPROM **80** that can be written to by μC **23** or via bus B are similarly possible; cf. for example PCT Application PCT/EP99/05186 of the Applicant, dated Jul. 21, 1999 whose US national phase is Ser. No. 09/ 720,221.

The two outputs SDA **81** and SCL **83** are configured as open collector outputs, and are therefore wired to pull-up resistors **85** and **87**, respectively.

Setpoint frequency f_s is furnished externally, e.g. from a frequency generator or another motor. Actual frequency f is in this case furnished by sensor **61**, which furnishes a constant number of pulses per revolution. Any known type of sensor can be used as sensor **61**, e.g. a resolver; a tachogenerator that furnishes an alternating voltage at its output; a Hall generator; or an optical, inductive, or other sensor. Since, in electronically commutated motors, the rotor position is usually sensed by means of one or more Hall generators, the output signal of such a sensor can also be used as the actual frequency, since additional costs for a tachogenerator are then eliminated. The use of a tachogenerator may, however, be advantageous if a high frequency of signal f is desired for the actual frequency, for example if the rotation speed is low, e.g. in the case of a marine diesel with a very low rotation speed.

Filters FILT_s **51** and FILT **57** serve to condition the edges of setpoint frequency f_s and actual frequency f, respectively, so that the presence of an edge at the respective interruptible inputs B**5** **42** and B**4** **43** reliably triggers an interrupt. Filters FILT_s **51** and FILT **57** can be configured, for example, as RC members or as Schmitt triggers.

With appropriate signals f and f_s, one or both of filters FILT_S **51** and FILT **57** can also be omitted.

An example of the effect of the filters is shown in FIG. **4**.

FIG. 4A shows actual frequency f before it has entered filter FILT **57**, and FIG. 4B shows actual frequency f after it has been conditioned in filter FILT **57**.

Actual frequency t in FIG. 4A derives, for example, from a Hall generator, and its edges **109** are less steep.

Actual frequency f in FIG. 4B has been conditioned by filter FILT **57**. Edges **110** are steep, and can reliably trigger an interrupt in μC **23**.

A control output RGL_VAL calculated in μC **23** (FIG. 7) is outputted via terminal C**1** **41** as a pulse width modulated (PWM) signal PWM_SW. Signal PWM_SW is converted by an RC member comprising resistor **65** and capacitor **67** into an analog voltage approximately proportional to μC-internal control output RGL_VAL, which voltage is designated as control output SW and is delivered to adjusting member SG **63** via line **27**. Adjusting member SG **63** controls the delivery of current for motor M **32**. Adjusting member SG **63** can be configured, for example, as an analog longitudinal positioner, or as a PWM adjusting member, or in another fashion.

FIG. 5A shows PWM signal PWM_SW from terminal C**1** **41** of FIG. 3; and FIG. 5B shows, in idealized form, control output SW that is created at node **66** of FIG. 3 by the RC member constituted by resistor **65** and capacitor **67** as the pulse duty factor of PWM_SW decreases.

Depending on pulse duty factor TV_SW of PWM signal PWM_SW of FIG. 5A, control output SW of FIG. 5B has a specific voltage u between 0 and MAX.

Pulse duty factor TV is generally defined as

*t*_on/*T* (2)

i.e. as the quotient of the time t_on (FIG. 5A) during which the PWM signal is HIGH (here from 121 to 123), and the period T of the PWM signal (here from 121 to 125). The pulse duty factor is indicated as a percentage, and can therefore assume values from 0 to 100 percent.

In FIG. 5A, the pulse duty factor decreases from left to right, so that signal SW in FIG. 5B also decreases from left to right.

Signal SW is delivered to adjusting member SG **63** of FIG. 3 via line **27**, so that the motor rotation speed can be controlled by means of pulse duty factor TV_SW.

FIG. 6A shows, purely by way of example, an exemplary embodiment for adjusting member SG **63** of FIG. 3 that serves to control rotation speed n of a motor **137**, which is depicted here as a collector motor.

Adjusting member SG **63** comprises a comparator **131** having a positive input **132** and a negative input **133**, a triangular generator DG **134**, and an npn transistor **135**.

From node **66**, signal SW is delivered to positive input **132** of comparator **131**. Triangular signal u_D generated by triangular generator DG **134** is delivered to negative input **133** of comparator **131**. A PWM signal PWM_M is created at the output of comparator **131** and is delivered to transistor **135**. Transistor **135** switches between operating voltage +U_B connected via line **33** and motor M **137**, which is connected via line **35** and has associated with it a tachogenerator **138** for producing a frequency f proportional to the rotation speed.

FIG. 6B shows examples of profiles for voltages u_D and SW, and FIG. 6C shows a signal PWM_M resulting therefrom with which transistor **135** is switched on and off.

Comparator **131** compares the two signals u D and SW. If control output SW is greater than triangular voltage u_D, then PWM_M signal PWM_M is HIGH; otherwise it is LOW. The pulse duty factor of PWM signal PWM_M is thus controlled by means of the magnitude of control output SW. In FIG. GB, signal SW increases from left to right. As a result, the pulse duty factor of signal PWM_M in FIG. 6C is also increased from left to right.

Since motor **137** also receives more current and therefore more output via transistor **135** when the pulse duty factor of signal PWM_M is higher, the motor rotation speed can be controlled by way of the magnitude of control output SW.

FIG. 29 shows a variant of FIG. **6**. Identical or identically operating parts are therefore given the same reference characters as in FIG. **6**. The motor is depicted here as a so-called two-phase, two-pulse electronically commutated motor (ECM) **32**″ which has, as an example, a two-pole permanent-magnet rotor **732**. The latter controls, through its magnetic field, a Hall generator **61** which generates signal f and with that signal also controls the commutation of ECM **32**″. ECM **32**′ can be constructed, for example, in accordance with DE 23 46 380 C2 and corresponding Müller U.S. Pat. No. 3,873,897. This is, of course, only one example. The invention is similarly suitable for ECMs having a different number of phases and a different number of rotor poles, as is self-evident to one skilled in the art.

The two phases of ECM **32**″ are labeled **736** and **738**. Current i**1** in phase **736** is controlled by an npn Darlington transistor **740** with free-wheeling diode **742**, and an npn Darlington transistor **744** with free-wheeling diode **746** serves to control current i**2** in phase **73**B. The emitters of transistors **740**, **744** are connected to one another and, through a resistor **74**B, to GND.

Transistor **740** is controlled by a port OUT**1** of μC **23** via an AND element **750**, which has signal PWM_M delivered to its other output from PWM adjuster **63**. FIG. 29 schematically shows the shape of that output signal, which comprises square-wave pulses at, for example, 25 kHz. The width of said pulses is determined by the magnitude of the voltage at input **132** of adjuster **63**. Transistor **740** becomes conductive only if a logical “1” signal is present both at the output of adjuster **63** and at output OUT**1** of μC **23**.

Transistor **744** is similarly controlled by a port OUT**2** of μC **23** via an AND element **752**, which has signal PWM_M delivered to its other input from adjuster **63**. Transistor **744** therefore becomes conductive only if a logical “1” signal is present both at the output of PWM adjuster **63** and at output OUT**2** of μC **23**.

A resistor **754** is located between the output of AND element **750** and the base of transistor **740**, and a resistor **756** is present analogously for transistor **744**.

As described below with reference to FIG. 13, S**310** and S**314**, outputs OUT**1** and OUT**2** of μC **23** are switched alternatingly to HIGH and LOW and thereby control which of the two phases **736**, **738** is to receive current. The magnitude of currents i**1**, i**2** is determined by the signal at node **66**, which determines the pulse duty factor of signal PWM_M, as described in detail in FIG. **6**.

FIG. 7 shows an overview of the program executing in μC **23**. The program comprises a setpoint measurement function “MEAS_f_s” **141** and a setpoint calculation function “CALC n_s” **143**, an actual value measurement function “MEAS f” **147** and an actual value calculation function “CALC n” **149**, a “gearbox” **145**, and rotation speed controller n-CTRL **35** (FIG. **1**). The digital rotation speed controller n-CTRL **35** has in this case a system deviation calculator **151**, a PI controller “PI-RCL” **153**, and a control output generator “GEN PWM” **155** at whose output signal PWM_SW is generated.

Setpoint frequency f_s is measured in “MEAS f_s” **141**. Here the number of edges (**110** in FIG. 4) since the last measurement is measured in a variable INT_MEAS_f_**3**, and the instant of the present measurement is measured in a variable t_MEAS_f_s.

Setpoint calculation function “CALC n_s” **143** calculates therefrom the rotation speed setpoint n_s. This is explained below with reference to FIG. **15**.

The measurement of actual frequency f in “MEAS f” **147** and the calculation of actual rotation speed n in “CALC n” **149** occur in a fashion entirely analogous to the measurement of setpoint frequency f_s in “MEAS f_s” **141**, and rotation speed setpoint n_s is calculated in “CALC n_s” **143**.

In “X*n_s” rotation speed setpoint n_s is multiplied by a factor X, and that product as well as actual rotation speed n is delivered to system deviation calculator **151**. If X=2, for example, the result is that twice the value of the measured rotation speed setpoint is delivered to system deviation calculator **151**; while if, for example, x=½, a value corresponding to half the rotation speed setpoint is delivered to system deviation calculator **151**. “X*n_s” thus implements a gearbox function; it is highly advantageous that factors such as, for example, X=1.733 can also be set in this context.

FIG. 7 also shows, with dashed lines, a variant w-th block **145**′, in which actual rotation speed n is multiplied by a factor Y. Variant **145** (i.e. X*n_s) is normally preferred, since then all the motors of a system can be of identical design and the gearbox factor X can be set globally according to the same rules.

A system deviation RGL_DIFF calculated in system deviation calculator **151** is delivered to controller function “PI-RGL” **153**, which calculates controller value RGL_VAL therefrom. The manner in which this is done is described in detail below with reference to FIG. **18**.

Value RGL_VAL is delivered to control output generator “GEN PWM” **155**, which converts it (in this example) into a PWM signal PWM_SW that is outputted at output C**1** of μC **23** and is described in more detail in FIG. **5**. By means of signal PWM_SW, the rotation speed of motor M is controlled so that system deviation RGL_DIFF becomes zero.

The architecture of the overall program executing in μC **23** will be described below using a preferred exemplary embodiment. The subprograms will then be described individually. They are designed specifically for an inexpensive microcontroller. If an expensive processor is used, other approaches are also possible in the context of the invention, but the version described has the advantage that it can be implemented at very low cost, so that great savings can be realized as compared to a mechanical gearbox.

FIG. 8 shows a flow chart with a preferred embodiment of the overall program executing in μC **23**.

At the very top are three interrupt routines—Hall Interrupt S**631** (FIG. **13**), f_s Interrupt S**635** (FIG. **14**), and TIMER**0** Interrupt S**639** (FIG. **12**)—which are executed each time the respective interrupt **630**, **634**, or **638** occurs and which act on the main program via **632**, **636**, **640**. The priority, i.e. the sequence in which the individual program elements are executed, decreases from the top down. The priorities are therefore labeled l L**1** through L**10** along the right side, L**1** having the highest priority.

The main program is depicted below the interrupt routines. After motor **32** is switched on, an internal reset is triggered in μC **23**. Initialization of μC **23** occurs in S**600**. For example, parameters are read out of EEPROM **80** and transferred into the RAM of μC **23**.

After initialization, execution branches into a so-called function manager **601** that begins in S**602**. Function manager **601** controls the execution of the individual subprograms.

Those functions that are time-critical and must be performed at each pass are executed first. These include, for example, a communication function COMM in S**604** which performs data transfer between μC **23**, EEPROM **80**, and external bus terminal B. S**606** represents any further time-critical functions that may be present.

FIG. 9 shows an example of a function register **605** in which one bit is reserved for each further function in FIG. **8**.

In this exemplary embodiment function register **605** is one byte long, and the following request bits, starting with the least significant bit (LSB), are defined for the requestable functions that are explained later:

FCT_XY for any function S**612**;

FCT_CALC_n for an actual value calculation function CALC_n S**616** (FIG. **15**);

FCT_CALC n s for a setpoint calculation function CALC_n s S**620** (FIG. **16**);

FCT_RGL_ON for a controller start check function RGL_ON S**624** (FIG. **17**);

FCT_RGL for a controller function RGL S**628** (FIG. **18**).

The remaining bits (bit**5** through bit**7**) are reserved for additional requestable functions that may be integrated into function manager **601** as applicable.

Actual value calculation function CALC n S**616** (FIG. 15) serves to calculate actual rotation speed n; setpoint calculation function CALC n_s S**620** (FIG. 16) serves to calculate rotation speed setpoint n_s; and controller start check function RGL_ON S**624** (FIG. 17) checks whether the conditions exist for initiating the subsequent function RGL S**628** (FIG. **18**), and requests that function as applicable. Lastly, controller function RGL S**628** calculates the new control output RGL_VAL (FIG. 7) and outputs it to adjusting member SG **63** of motor **32**.

If a specific requestable function is to be requested by another function or by an interrupt routine, the bit of the requested function in function register **605** (FIG. 9) is set to 1, e.g. FCT_XY=1. If function manager **601** finds no other requestable function with a higher priority during a pass, that function is executed.

Once a requested function has been executed, it sets its own request bit back to 0, i.e. for example FCT XY=0. This allows longer functions—which cannot be executed in one pass because, for example, they would take too long—to be subdivided and processed in multiple calls.

In FIG. 8, after S**606** the program checks in a predetermined sequence, beginning with the most important requestable function, as to whether each function's request bit is set. If such is the case for a function, it is executed; and execution then branches back to the beginning FCT_MAN S**602** of function manager **601**. The sequence in which function register **605** is checked defines the prioritization of the requestable functions. The higher up a function is located in function manager **601**, the higher its priority.

The mode of operation of function manager FCT_MAN **601** will be explained with reference to an example. If the program branches, for example, from S**610** to S**614**, S**614** then checks whether function register bit FCT_CALC_n=1, i.e. whether actual value calculation function CALC_n S**616** (depicted in FIG. 15) has been requested. If Yes, execution branches to S**616** and the rotation speed calculation is performed. Upon termination, rotation speed calculation function CALC_n S**616** resets request bit FCT_CALC_n back to 0 (cf. S**374** in FIG. **15**), and execution branches back to the beginning S**602** of function manager **601**.

If a request bit was not set in any of the polls up to S**626**, execution branches without any action back to S**602**, and functions S**604** and S**605**, which are executed at each pass of function manager **601**, are performed again.

The function manager results in optimum utilization of the resources of μC **23**.

The measurements of actual frequency f and setpoint frequency f_s proceed identically but independently of one another. It could also be said that they proceed in quasi-parallel fashion, “quasi-” meaning that a true parallel processor (which would also be possible in the context of the invention) is not used in this exemplary embodiment. The discussion below will first address the measurement of actual frequency, the actual frequency being an indication of the rotation speed of motor **32** (FIG. **3**).

FIG. 22 shows a rotor **32** having a mark **290**, and a sensor **61** for mark **290** that serves as rotor position sensor. Rotor **32** is usually part of a motor M. If this is an electronically commutated motor (ECM), it usually has a rotor position sensor **61** which can then also be used for the present invention.

By means of mark **290**, rotor position sensor **61** detects a rotor position signal f. Rotor position signal f comprises pulses at points **265**, **266**, **267**, and **268**, etc., one revolution of rotor **32** having taken place between each two pulses. The time axis is labeled t. These pulses represent “events” in the rotation of rotor **32**. In FIG. 22, one event (i.e. one pulse) is generated for each rotor revolution.

By means of rotor position signal f, the rotation speed of rotor **32** is measured as described below. At regular intervals T_A a start signal **261**, **263**, etc. is generated, requesting a new measurement each time.

The start signal at point **261** is followed by pulse **265**, and the start signal at point **263** is followed by pulse **266**. The measurement takes place between points **265** and **268**. The number N of pulses of rotor position signal f occurring after **265** up to and including **268** is measured (i.e. N=3 in this case), as well as the time Δt(**265**-**268**) required for said pulses. The frequency of rotor position signal f, and thus the rotation speed of rotor **32**, can be determined therefrom. At each of points **265**, **268** of the measurement, an old measurement is terminated and a new measurement is started. The procedure is therefore such that, at the pulse following start signal **261**, **263**, an old measurement is terminated and a new measurement simultaneously begun each time.

The number N of pulses can be measured, for example, in a counter, by the fact that in said counter, the value N at the end of each measurement is reset to zero and the counter value N is then incremented by 1 at each pulse.

The time Δt can be measured, for example, by taking the difference between the time at which the measurement starts, e.g. t(**265**) at point **265**, and the time at which the measurement ends, e.g. t(**268**) at point **268**.

For example, if t(**265**)=17.7 ms and t(**268**)=87.7 ms,

then

Δt(**265**-**268**)=87.7−17.7=70 ms.

Start signals **261**, **263**, which occur at fixed intervals T_A, create a measurement window. The measurements do not, however, take place exactly at the instant of the respective start signal; instead, measurement occurs at a suitable point, subsequent to the respective start signal, at which a pulse (“event”) of rotor position signal f occurs. If a measurement were made at the instant of the respective start signal, the beginning and the is end of the measurement would take place, in most cases, at a point between two pulses of the rotor position signal. This would result in an inaccurate measurement. Waiting until the next pulse, however, means that complete periods between the pulses are measured, resulting in a great increase in measurement accuracy.

FIG. 23 schematically shows a calculation of rotation speed n in a rotation speed calculation function **270**. Function **270** receives as input, at time intervals having an average duration T_A, the number N of pulses and the time Δt required for that number N. Function **270** calculates therefrom a rotation speed datum n as the quotient of number N and time Δt:

*n=N/Δt* (3)

FIG. 24 shows rotor **32**′ (of a motor M_**2**) having two marks **291** and **292**, and rotor position sensor **61**. Marks **291** and **292** are offset by approximately 180° mech.

Rotor position **61** senses a rotor position signal f by means of marks **291** and **292**. Rotor position signal f has pulses resulting from mark **291** (shown in solid white) at points **276**, **278**, **280**, and **282**, and pulses resulting from mark **292** (shown in solid black) at points **275**, **277**, **279**, and **281**. Between each two “white” pulses and between each two “black” pulses, rotor **32** has rotated once.

Since the pulses generated by marks **291** and **292** cannot be distinguished, it may be stated more generally that one complete revolution of rotor **32** takes place between each pulse and the next pulse but one (e.g. between N=1 and N=3).

The following considerations underlie the measurement of rotation speed n of rotor **32**, in FIG. **24**:

Marks **291**, **292** can never be arranged absolutely symmetrically. If it is assumed that mark **291** is located at 0° mech., mark **292** would need to be located exactly at 180° mech. Due to mechanical defects, however, it may be positioned at, for example, 183° mech. This would result, for the case of a measurement that begins at point **276** (mark **291**) and ends at point **281** (mark **292**), in a measurement error, since the angular range being measured is then not an exact multiple of 180° mech.

To solve this problem, only complete revolutions are measured in each case in FIG. 24; i.e. measurement always takes place between marks of the same type, so that an exact multiple of 360° mech. is always measured. The measurement that begins at **276** (i.e. after starting pulse **271**) therefore ends not at point **281** but at point **282**, which is the next point after start signal **273** at which one complete revolution (considering the measurement to have started at point **276**) has once again taken place.

This condition can be described mathematically using the MODULO (mod) function; for example,

**2**=0 (4)

means that when the value N is divided by 2, a remainder of 0 is left. For example, 0 mod **2**=0, 1 mod **2**=1, 2 mod **2**=0, 3 mod **2**=1, etc. Similarly, 0 mod **4**=0, 1 mod **4**=1, 2 mod **4**=2, 3 mod **4**=3, and 4 mod **4**=0, etc.

In FIG. 24, “N mod **2**” appears at **283** below pulses **275** through **282**, and a measurement ends/starts, for example, only if a measurement is requested by means of a start signal **271**, **273** and additionally if the condition N mod **2**=0 is met. Stated more generally, in FIG. 24 the value of N mod **2** must be the same at the beginning and at the end of the measurement.

If a rotor has a number of marks A, the condition stated in equation (4) is then generally

The variable A will be referred to hereinafter as MOD_f, i.e. A=MOD_f, and equation (5) then becomes

The first mark either can be selected by means of a particular signal, or the first measured signal can be selected as a pulse with N=0. This will be clarified even further in the explanation referring to FIG. **13**.

The measurement thus occurs either, as shown in FIG. 24, between “white” pulses or, as depicted on the right side of FIG. 15, between “black” pulses. In the example of FIG. 24, the measurement is accomplished between pulses **276** and **282**. N=6 pulses are counted in this case, and the time offset between pulses **276** and **282** is ascertained and equals Δt(**276**-**282**). A rotation speed datum n is then calculated from these two values using equation (3).

Let it be emphasized that in reality there are no “white” or “black” pulses; rather these are a didactic aid for explanation of one aspect of the invention.

FIG. 25 shows, by analogy with FIG. 24, a rotor **32** having two marks **781** and **782**, and rotor position sensor **61**. Rotor position signal f comprises events in the form of pulses at points **717**, **718**, **719**, . . . , **728**. The pulses are generated alternately by white mark **781** and black mark **782** as the latter rotate past rotor position sensor **61**, and are therefore, for better comprehension, depicted in white and black. In addition, an interference pulse S occurs between pulses **720** and **721**. Control signals **711**, **713**, and **715** for requesting a measurement are also depicted.

Beneath the pulses, the value of counter N for the number of pulses is indicated in row **732**, and the result of the calculation of N mod **2** is shown in row **730**.

A measurement normally ends/begins whenever a measurement is requested by means of a control signal **711**, **713**, or **715**, and the value of N mod **2** is also equal to zero, i.e. when rotor **32**′ has rotated an integral multiple of one revolution since the last measurement.

The result of interference pulse S is that in the context of the measurement in the time period Δt(**718**-**723**), it is assumed that rotor **32**′ has completed one entire revolution between pulses **720** and **721**, even though it has completed only half a revolution. As a result, after control signal **713**, measurement occurs not at the “white” signal **722** but at the “black” signal **723**, since after interference pulse S, it is no longer at the “white” pulses but at the “black” pulses that N mod **2** has a value of zero.

Measurement is already proceeding correctly again in the following time period Δt(**723**-**727**), however, since measurement is now occurring at each of the “black” pulses. What occurs as a result of interference pulse S is therefore a displacement of the position of rotor **32**′ at which measurement takes place. The same would be true if a pulse were missing. The measurement method thus continues to work correctly after an incorrect signal S, and once again measures a multiple of one complete revolution. This represents an important advantage of this embodiment.

FIG. 10 shows a state diagram for measurement of the actual frequency. The state diagram comprises four states S**1**, S**2**, S**3**, and S**4**, and six transitions T**1**, T**2**, . . . , T**6**.

Each transition has an event and an action associated with it.

Table 1 below shows the associated event and associated action for each transition.

Transition | Event | Action |

T1 | Interrupt due to edge of | Read and store TIMER1, |

signal f | increment INT_CNT_f | |

T2 | Interrupt due to TIMER0 | Enable actual value and |

after time T_A | setpoint calculation and | |

controller | ||

T3 | Interrupt due to edge of | Read and store TIMER1, |

signal f | increment INT_CNT_f | |

T4 | INT_CNT_f mod MOD_f = 0 | Calculate t_MEAS_f, |

INT_MEAS_f, start | ||

CALC n | ||

T5 | Instantaneous | None |

T6 | Instantaneous | Prepare for new |

measurement | ||

FIG. 11 shows a related diagram with an example of a procedure for measuring setpoint frequency f_s and actual frequency f.

FIG. 11A shows interrupts **161**, **163**, **165** of a timer TIMER**0** (in μC **23**) which are triggered in each case after a time T_A, e.g. T_A=25 ms.

FIG. 11B shows setpoint frequency f_s which is delivered to μC **32**, e.g. from frequency generator **20** (FIG. **1**). At each of points **167**, **169**, and **171**, the two variables INT_MEAS_f_s (for the number of edges since the last measurement) and t_MEAS_f_B are forwarded to the setpoint calculation function along with the instant of the present measurement determined by means of timer TIMER**1**. The numbers in parentheses designate the particular instant or time range to which the particular value applies. At instant **169**, for example, the value INT_MEAS_f_s(**167**-**169**) which contains the number of edges in the range from **167** to **169**, and the value t_MEAS_f_s(**169**) which contains the instant of the measurement at **169**, are forwarded to setpoint calculation function CALC_n_s S**620** (FIG. **8**).

FIG. 11C shows, by analogy with FIG. 11B, actual frequency f that is detected by rotor position sensor **61**. INT_MEAS_f and t_MEAS_f are determined at points **175**, **177**, and **179**.

The frequency measurement procedure will now be explained with reference to FIG. 10, Table 1, and FIG. **11**. The measurements of setpoint frequency f_s and actual frequency proceed according to the same pattern. The measurement principle will therefore be explained first with reference to the measurement of actual frequency f.

At instant t=0 selected arbitrarily in FIG. 11, the actual value measurement function is in state S**1**.

At each edge **110** (FIG. 4B) of f, a Hall interrupt **630** (FIG. 8) is triggered, with the following results:

Hall interrupt routine S**631** (FIG. 13) is triggered by Hall interrupt **630**;

in Hall interrupt routine S**631**, counter INT_CNT_f for the number of edges is incremented by a value INC_f, e.g. INC_f=1 (S**322** in FIG. **13**);

the instantaneous value of ring counter TIMER**1** is stored in Hall interrupt S**631** (S**322** in FIG. **13**).

In the state diagram (FIG. **10**), this is depicted as transition T**1** from state S**1** to S**1**. The event here is a Hall interrupt **630** triggered by an edge **110**, and the action consists in counting edge **110** in edge counter INT_CNT_f, and storing the instantaneous value of ring counter TIMER**1**.

A different event triggers transition T**2** from state S**1** to state S**2**. The event is an occurrence of a TIMER**0** interrupt triggered by timer TIMER**0**. TIMER**0** triggers a TIMER**0** interrupt **683** at defined intervals T_A (FIG. **11**A), e.g. at points **161**, **163**, **165**. In the associated interrupt routine TIMER**0** Interrupt S**639** (FIGS. **8** and **12**), actual value calculation, setpoint calculation, and the controller are enabled. TIMER**0** defines successive windows having a width T_A.

The actual measurement of INT_MEAS_f and t_MEAS_f will then take place. As is apparent from points **175**, **177**, and **179**, the measurement in question takes place not precisely at instants **161**, **163**, and **165** when requested, but at a suitable instant that is usually slightly later in time than the instant of the request.

Edges **110** of signal f are also sensed in state S**2**, and at each edge **110** a transition T**3** from S**2** to S**2** (analogous to T**1**) takes place, in which the instantaneous value of ring counter TIMER**1** is read out and stored, and edge counter INT_CNT_f is incremented.

One further condition must be met in order for values INT_MEAS_f and t_MEAS_f finally to be measured. The poles of a permanent-magnet rotor having, for example, four poles usually do not have an extension (pole width) of exactly 90° mech., but deviate slightly therefrom. The sum of all the pole angles always, however, equals 360° mech. It is therefore advantageous, for example in the context of a measurement with Hall sensors, to measure only every complete revolution, i.e. every fourth edge in the case of a four-pole rotor, since this ensures that measurement always takes place exactly at the same point on rotor **32**. For a more detailed explanation, please see the description of FIG. **24**.

The number of edges **110** of signal f is counted in variable INT_CNT_f, and the condition that, in the case of a four-pole rotor, a multiple of complete revolutions is always measured can be met, based on the description of FIG. **24** and equation (5), if

**4**=0 (5)

or alternatively if

**3**=0;

in the latter case, measurement always occurs, at the earliest, after two complete revolutions or a multiple thereof. If INT_CNT_f mod **12**=0, measurement would occur at the earliest after three complete revolutions, etc. The dynamics of a controller would thereby be impaired, however.

For a six-pole rotor, it would correspondingly be possible to work with, for example, INT_CNT_f mod **6**=0, or with INT_CNT_f mod **12**=0.

Therefore, if the number of edges is a multiple of MOD_f (in this case MOD_f=4), in FIG. 10 a transition T**4** from S**2** to S**3** takes place; the number of edges sensed since the last measurement, which is stored in INT_CNT_f, is stored in INT_MEAS_f (S**330** in FIG. **13**); and the instant of the present measurement is stored in t_MEAS_f. The values INT_MEAS_f and t_MEAS_f are then transferred to actual rotation speed calculation function CALC_n S**616**, which is depicted in FIG. **15**.

In FIG. 11, for example, if after TIMER**0** interrupt **163** at actual frequency f a multiple of MOD_f=4 edges—i.e. in this case, for example, eight edges (**8** mod **4**=0)—has been sensed at instant **177**, then the number of edges since the last measurement is stored in INT_MEAS_f(**175**-**177**) for instant **177**, and instant **177** of the present measurement is stored in t_MEAS_f(**177**).

From the present value t_MEAS_f(**177**) and the stored value t_MEAS_f(**175**) of the last measurement, it is possible to determine the time Δt_MEAS_f(**175**-**177**) required for the edges counted in variable INT_MEAS_f(**175**-**177**).

An alternative possibility for determining the time Δt_MEAS_f is to reset the time to zero at the beginning of each measurement. This can be done, for example, by setting timer TIMER**1** to zero. At the end of the measurement, the time then corresponds to the value Δt_MEAS_f. As a result, INT_MEAS_f and Δt_MEAS_f are available directly at points **175**, **177**, and **179**. A disadvantage of resetting TIMER**1** is the difficulty of then using it simultaneously for other measurements, so that further counters may be required; this is not excluded, however, in the context of the present invention.

From state S**3**, in which the last measurement is completed, an instantaneous transition T**5** leads to state S**4**, in which a new measurement begins.

From state S**4** an instantaneous transition T**6** leads to state S**1**, and the frequency measurement procedure is once again in the initial state S**1**. During T**6**, the next measurement is prepared; for example, counter INT_CNT_f (for the number of edges **110**) is reset back to zero.

The TIMER**0** interrupts **638** at points **161**, **163**, and **165** request both an actual frequency measurement and a setpoint frequency measurement. The measurement of setpoint frequency f_s proceeds in conformity with the measurement of the actual frequency, which is evident from the flow charts that follow.

The designations of the variables for setpoint acquisition are identical to those for actual value acquisition, except that an “_s” suffix is added; for example, INT_MEAS_f_s rather than INT_MEAS_f.

It may once again be advisable to measure a multiple of a fixed number of edges when defining a setpoint frequency f_s. For example, deviations may occur within one period of setpoint frequency f_s. A measurement of, for example, at least two edges in each case may therefore be advantageous. Edge counter INT_CNT_f_s must then be checked using INT_CNT_f_s mod **2**=0.

Measurement as defined in FIGS. 10 and 11 has several advantages.

With interrupt-based measurements, the rotation speed can be determined by measuring the time since the previous interrupt (either at each interrupt or after a fixed number of interrupts) and calculating the rotation speed therefrom. This means that as the rotation speed increases, new measured values that must be processed arrive with increasing frequency. At very high rotation speeds, this would result in an overload of μC **23** so that individual measured values would not be taken into account.

With the present measurement method, a new measurement is initiated each time at defined intervals T_A. The load on μC **23** is thus the same at all rotation speeds and frequencies.

The present method moreover has the advantage that when signals f and f_s are measured, measurement occurs at least up to the next interrupt. Measurement therefore does not occur at some instant that lies, for example, in between two edges; instead, measurement always takes place from edge to edge, greatly increasing measurement accuracy.

A further increase in measurement accuracy is obtained by always measuring a multiple of MOD_f or MOD_f_s edges, thereby eliminating, for example, measurement errors resulting from magnetization defects in a permanent-magnet rotor or from symmetry errors in the setpoint frequency definition. This means, for example in the case of a four-pole motor, that a measurement takes place at the earliest at the fourth, eighth, 12th, etc. edge, i.e. whenever X mod **4**=0 (with a four-pole rotor, four edges **110** are generated for each revolution).

An additional great advantage is the fact that both the actual value measurement and the setpoint measurement are started at each expiration of a time T_A, since the results of the two measurements are thus available to controller function RGL practically simultaneously. If a measurement were made after each edge, the signal would be measured more often as the frequency increased; this would be less favorable in terms of downline processing.

The use of the same timer (TIMER**1**) for measuring f and f_s is extraordinarily advantageous, since an inaccuracy in the timer does not result in any inaccuracy in the time ratio between the measurements of f and f_s. Frequencies f and f_s are thus measured with the same time track. A measurement procedure of this kind very advantageously makes possible frequency-controlled rotation speed control with a gearbox function. A measurement of this kind using the same timer is described below with reference to an example.

TIMER**1** is preferably configured as a ring counter that runs continuously.

FIGS. 12 through 14 show flow charts pertaining to a program for the measurement procedure described in FIGS. 10 and 11.

FIG. 12 shows routine TIMER**0** Interrupt S**639** (FIG. 8) which, after each time T_A (FIG. **11**), requests actual value measurement “MEAS f” **147** (FIG. **7**), setpoint measurement “MEAS f_s” **141** (FIG. **7**), and digital rotation speed controller n-CTRL **35** (FIGS. 1 and 7) constituted by RGL_ON S**624** and RGL **5628** (both FIG. **3**).

The following variables are used:

CNT_T_A Internal counter for time T_A

T_A_TIME Limit value for new measurement

DO_MEAS_f Flag to call actual value measurement

DO_MEAS_f_s Flag to call setpoint measurement

FCT_RGL_ON Function register bit of function RGL_ON S**624** (cf. FIG. **9**).

Routine TIMER**0** Interrupt S**639** depicted in FIG. 12 is executed each time a TIMER**0** interrupt **638** (FIG. 8) occurs.

In S**352** any additional steps not discussed here can be run through, if TIMER**0** is additionally intended to control other program sections.

A subtimer Subtimer_T_A begins in S**354**. “Subtimer” means that the actual action in S**360** is triggered by steps S**356**, S**358**, and S**362** (explained below) only after a specific number of TIMER**0** interrupts. The advantage of this is that timer TIMER**0** can also be used for other duties that need to be called more frequently.

In **5356**, internal counter CNT_T_A is incremented by 1.

S**358** checks whether counter CNT_T_A is greater than or equal to the value T_A_TIME (defined above).

If No, execution branches immediately to the end S**364**, and leaves the TIMER**0** Interrupt routine with the instruction “RETI.”

If, however, it is found in **535**B that counter CNT_T_A has reached the value T_A_TIME, then in S**360** DO_MEAS_f_s, DO_MEAS_f, and FCT_RGL_ON are set to 1.

DO_MEAS_f_s=1 informs interrupt routine f_s Interrupt S**635** (FIG. 14) that a measurement of setpoint frequency f_s is to be started. DO_MEAS_f=1 informs interrupt routine Hall Interrupt S**631** (FIG. 13) that a measurement of actual frequency f is to be started. FCT_RGL=1 starts start function RGL_ON S**624** (FIG. **17**), which determines when controller function RGL S**628** (FIG. 18) is started.

An example: if TIMER**0** Interrupt is triggered every 10 microseconds, and the value T_A_TIME=2500, the call in S**360** takes place every 25 ms.

Time T_A must be adapted to the particular motor. For example, if rotor position sensor **61** produces many events for each revolution of rotor **32**, and if rotor **32** is rotating quickly, T_A can be made shorter. If rotor **32** is rotating slowly, however, T_A must then be made longer, e.g. TA=250 ms. Frequency f_s must be considered in the same fashion.

In S**362**, counter CNT_TA is reset back to zero in order to restart subtimer Subtimer_T_A.

In FIG. 11, S**360** is called at points **161**, **163**, and **165**.

FIG. 13 shows an exemplary embodiment of interrupt routine Hall Interrupt S**631**, which is executed at each interrupt triggered by the occurrence of an edge **110** (FIG. 4B) of signal f. This interrupt is so designated because it is usually triggered by the signal of a Hall generator **61**. FIG. 29 shows an example of this. Of course it could also be triggered by the signal of an optical or mechanical sensor, and it could also be referred to as a “sensor-controlled” interrupt.

In this example, routine Hall Interrupt S**631** provides commutation of an electronically commutated motor **32** in steps S**304** through S**314**, and measurement of actual frequency f in steps S**320** through S**332**.

The following variables are used:

INT_CNT_f Interrupt counter for counting the edges of signal f

INC_f Increment value

t_END_f Instant of last interrupt sensed

MOD_f Number of interrupts for mod calculation (cf. equation (5a))

t_MEAS_f Measured time of last interrupt

INT_MEAS_f Number of interrupts measured since last measurement

DO_MEAS_f Flag to call actual value measurement

FCT_CALC_n Function register bit of function CALC_n S**616** (FIGS. **8** and **9**).

In S**302**, any desired steps can be executed.

In an electronically commutated motor (such as the one schematically depicted in FIG. **29**), routine Hall Interrupt S**631** provides electronic commutation in COMMUT S**304**. This is omitted in a collector motor such as the one depicted in FIG. **6**.

In S**306**, HALL=1? checks whether signal f (FIG. 4B) is HIGH. If Yes, then in **5308**, terminal B**5** of μC **23** (FIG. 3) is set so that it triggers an interrupt at the next edge from HIGH to LOW. (Another alternative possibility is a so-called “interrupt on change,” i.e. an interrupt takes place at every edge of signal HALL at port B**5**, regardless of direction.) Lastly, in S**310** commutation of motor M **32** takes place by the fact that OUT**1** is set to 1 and OUT**2** to 0. If it was found in S**306** that HALL equaled 0, then in S**312** terminal B**5** is set to an opposite edge, and in S**314** OUT**1** is set to 0 and OUT**2** to 1. Commutation using the two signals OUT**1** and OUT**2** has already been described exhaustively with reference to FIG. **29**.

Sensing and measurement of signal f begin in MEAS_f S**320**. In S**322**, interrupt counter INT_CNT_f, which is, for example, 1 byte long, is incremented by the value INC_f, e.g. INC_f=1, and the value t_TIMER**1** of TIMER**1** is stored in t_END_f. Both the number of interrupts and the instantaneous time are thus sensed.

In S**324**, INT_CNT_f mod MOD_f=0 is used to check whether the value in interrupt counter INT_CNT_f is a multiple of MOD_f. For MOD_f=4, for example, INT_CNT_f=20 is a multiple of MOD_f, i.e. 20 mod **4**=0. If INT_CNT_f is not a multiple of MOD_f, execution then branches to the end S**334** of the interrupt routine. If INT_CNT_f is a multiple of MOD_f, S**326** then checks whether DO_MEAS_f=1, i.e. whether a measurement of actual frequency f was requested in step S**360** of interrupt routine TIMER**0** Interrupt S**639** (FIG. **12**). If No, then no measurement is to take place, and execution branches to the end S**334**. If Yes, then in S**328** function register bit FCT_CALC_n is used to check whether the last rotation speed calculation is already complete. If FCT_CALC n=1, execution branches to the end S**334**. This prevents measurements from being lost if rotation speed calculation routine “CALC_n” S**616** requires too much time. This special case does not, however, occur in normal operation.

In S**330**. variables t_MEAS_f and INT_MEAS_f, which are transferred to rotation speed calculation routine CALC_n **5616** (FIG. **15**), are set.

This is done by setting t_MEAS_f to the last timer value t_END_f of ring counter TIMER**1** that was sensed, setting INT_MEAS_f to the value of interrupt counter INT_CNT_f, and resetting INT_CNT_f to zero.

In S**332**, rotation speed calculation routine CALC_n S**616** (FIG. 15) is requested by setting FCT_CALC_n to 1; and the measurement request is reset by resetting DO_MEAS_f to zero, since the measurement is complete.

Routines TIMER**0** Interrupt S**639** (FIG. 12) and HALL Interrupt S**631** (FIG. 13) thus together constitute a measurement of actual frequency f in accordance with the state diagram of FIG. **10**.

If μC **23** does not have the capability for the mod operation, there are other possibilities.

In many μCs, an integral division using “div” yields as the result both the integral quotient and the non-negative remainder. For example, the result of 7 div 4 is a quotient 1 and remainder 3. In these μCs, the div operation can be used to calculate the remainder.

A further possibility for calculating X mod MOD_f is, for example, to use a further variable MOD_CNT which is also incremented at each incrementing of variable X, and which is reset to zero each time MOD_f is reached. The MOD_CNT variable then contains the result of X mod MOD_f.

FIG. 14 shows an example of interrupt routine f_s Interrupt **5635**.

This is configured, except for the absence of the commutation portion (steps S**304** through S**314**), like interrupt routine HALL Interrupt S**631** (FIG. **13**), and therefore will not be described again. The reference characters of the steps are increased by 100, so that, for example, step S**332** of FIG. 13 corresponds to step S**432** of FIG. **14**.

The following variables are used:

INT_CNT_f_s Interrupt counter for counting the edges of the setpoint frequency

INC_f_s Increment value

t_END_f_s Instant of last interrupt sensed

MOD_f_s Number of interrupts for mod calculation

t_MEAS_f_s Measured time of last interrupt

INT_MEAS_f_s Number of interrupts since last measurement

DO_MEAS_f_s Flag to call setpoint measurement

FCT_CALC_n_s Function register bit for function CALC_n_s S**620**.

FIG. 15 shows routine CALC_n S**616**, which is requested by routine Hall Interrupt (S**332** in FIG. 13) after the measurement of timer value t_MEAS_f and of the number of edges **110** (FIG. 4) of signal f in INT_MEAS_f.

The following variables are used:

Δt_CALC_f Time difference from last measurement

t_OLD_f Instant of last measurement

t_MEAS_f Instant of present measurement

INT_CALC_f Number of interrupts since last measurement, for calculation

INT_MEAS_f Number of interrupts transferred since last measurement

n Rotation speed of motor M

REM_n Remainder of integral division

h Exponent for parameterization of INT_CALC_f

REM_n_OLD Remainder of integral division at last calculation.

In S**370**, the difference between timer value t_OLD_f for the last measurement and present timer value t_MEAS_f is calculated, and is stored in variable At_CALC_f, which corresponds to value [Δ]t_MEAS_f of FIG. **11**. In the context of a ring counter, the difference is usually obtained using the two's complement. Present timer value t MEAS_f is then stored in t_OLD_f for the next measurement, and the measured number of interrupts INT_MEAS_f is stored in INT_CALC_f.

In S**372**, a calculation is made of rotation speed n, which is proportional to the quotient of the number of interrupts INT_CALC_f (an indication of the number of revolutions) and the time Δt_CALC_f required therefor. The formula is

*n*=const*INT_CALC_f/Δt_CALC_{—} *f* (6)

where const is a proportionality constant.

An integral division div, which yields as the result an integral quotient n and positive remainder REM_n, is used to calculate rotation speed n. See FIG. 13 for a description of the div operator.

In addition, interrupt counter INT_CALC_f, which in this exemplary embodiment is, for example, 4 bytes long, is parameterized with a factor 2̂h, e.g. h=24. Any other factor can, of course, also be selected instead of 2̂h. Multiplication by 2̂h can, however, in preferred fashion, be replaced by displacement of the value h places to the left.

Parameterization results in good resolution, for example in a 16-bit context, of the rotation speeds resulting from division. The exponent h must, for this purpose, be matched to the particular motor.

Calculation of the rotation speed for the region between points **175** and **177** of FIG. 11 is shown below as an example:

INT_MEAS_f has a length of one byte, INT_CALC_f four bytes, and At_CALC_f two bytes.

INT_MEAS_f(**175**-**177**) here has a value of 8, i.e. eight edges **110** of signal f (FIG. 11C) have been counted since the last measurement at instant t_MEAS_f(**175**). In S**370** INT_CALC_f has the value INT_MEAS_f(**175**-**177**)=8 assigned to it. In S**372**, using h=19, INT_CALC_f is parameterized with 2̂19=524, 288, and acquires a value of 4, 194, 304.

Δt_MEAS_f(**175**-**177**) has a value of 26, 700, corresponding (if the resolution of ring counter TIMER**1** is 1 microsecond) to a time of 26.7 milliseconds. In S**370**, Δt_CALC_f has assigned to it a value of 26, 700, resulting from the difference between the old and present measurements.

Dividing INT_CALC_f by Δt_CALC_f yields a rotation speed n=157 and remainder REM_n 2404.

The physical rotation speed n_phys corresponds to the number of revolutions per minute. 8 Hall changes divided by 4 Hall changes per revolution (four-pole rotor) yields 2 revolutions, and time required therefor is 0.0267 s. This yields a physical rotation speed n_phys=2/0.0267=74.906 revolutions per second=4494.4 rpm.

The remainder REM_n_OLD of the previous rotation speed calculation is also taken into account in the calculation, by adding it to the product of INT_CALC_f and const_f.

In the above example, for instance, the calculated rotation speed n deviates slightly from the actual rotation speed, since division yields the whole number 157 rather than the actual result of approximately 157.09. The difference is not lost, however, but is taken into account in the subsequent division in S**372** by adding remainder REM_n_OLD of the previous division to the numerator.

The advantageous result of taking into account remainder REM_n_OLD is that no information is lost; and it results in a measurable improvement in the controller if it is used.

After the calculation of n and REM_n, in S**372** remainder REM_n is stored in REM_n_OLD for the next calculation.

In S**374**, function register bit FCT_CALC_n (FIG. 9; FIG. 13, S**332**) is reset back to zero, since the rotation speed calculation is complete.

Execution then branches back to the beginning S**602** of the function manager (FIG. **8**).

FIG. 16 shows a flow chart for calculating rotation speed setpoint n_s.

The following variables are used:

t_CALC_f_s Time difference from last measurement

t_OLD_f_s Instant of last measurement

t_MEAS_f_s Instant of present measurement

INT_CALC_f_s Number of interrupts since last measurement, for calculation

INT_MEAS_f_s Number of interrupts transferred since last measurement

n_s Rotation speed setpoint (desired rotation speed of motor M)

REM_n_s Remainder of integral division

h_s Exponent for parameterization of INT_CALC_f_s

REM_n_SOLD Remainder of integral division at last calculation.

The calculation of rotation speed setpoint n s is identical to the calculation of rotation speed n as shown in FIG. **15**. The reference characters of FIG. 16 correspond to those of FIG. 15 with 100 added to them. Value h_s for the parameterization of INT_CALC_f is normally selected to be identical to value h of FIG. 15, since the rotation speed setpoint and actual rotation speed should be comparable. Selecting h_s to be not equal to h would make relative parameterization possible, but this is normally not chosen.

To avoid excessive length, the steps of FIG. 16 will not be described again. The reader is referred to FIG. **15** and its accompanying description.

Since the measurements of setpoint frequency f_s and actual frequency f proceed in the same manner and in quasi-parallel fashion, a value for rotation speed setpoint n_s and a value for rotation speed n are present after each measurement triggered by the TIMER**0** interrupt. Values n and n_s are comparable because the times were measured, practically simultaneously, using the same timer TIMER**1**. In addition, they are very accurate because of the measurement methods used.

FIG. 17 shows a flow chart for an exemplary embodiment of function RGL_ON S**624** of FIG. 8, which determines when controller function RGL S**628** (FIG. 16) is started.

Since the sensing and measurement of actual frequency f and setpoint frequency f_s, and thus also the calculation of rotation speed n and rotation speed setpoint n_s, proceed independently of one another and do not end at the same instant, a determination must be made in function RGL_ON S**624** as to when controller function RGL S**628** is started. In this exemplary embodiment, controller function RGL S**628** is started when both actual rotation speed calculation routine CALC_n S**616** and rotation speed setpoint calculation routine CALC_n_s S**620** are complete.

The following variables are used:

FCT_CALC_n_s Function register bit for function CALC_n_s S**620** (cf. FIG. 9)

FCT_CALC_n Function register bit for function CALC_n S**616** (cf. FIG. 9)

FCT_RGL Function register bit for function RGL S**628** (cf. FIG. 9)

FCT_RGL_ON Function register bit for function RGL_ON S**624** (cf. FIG.

In S**390**, function register bit FCT_CALC_n_s is used to check whether rotation speed setpoint calculation CALC_n_s S**620** is ready. If No, execution branches back to the beginning S**602** of the function manager (FIG. **8**). If Yes, then in S**392**, function register bit FCT_CALC_n checks whether rotation speed calculation routine CALC_n S**616** is complete. If No, execution branches back to the beginning S**602** of the function manager. If Yes, then both rotation speed n and rotation speed setpoint n_s are present, and controller function RGL S**628** is requested by setting function register bit FCT_RGL to 1. Function register bit FCT_RGL_ON is reset to zero, since function RGL_ON S**624** has been executed.

Controller function RGL S**628** is therefore not started until rotation speed setpoint n_s and rotation speed n have been calculated.

FIG. 18 shows a flow chart for an embodiment of controller function RGL S**628** (FIG. 8) which calculates a control output RGL_VAL from rotation speed n and rotation speed setpoint n_s, and outputs it.

The following variables are used:

RGL_DIFF System deviation

X Gearbox factor

RGL_PROP Proportional component

RGL_P Proportional factor

RGL_INT Integral component

RGL_I Integral factor

RGL_VAL Control output calculated by controller

RGL_MAX Maximum control output.

In **5530**, system deviation RGL DIFF is calculated as

*n* _{—} *s*X−n* (7)

Multiplying rotation speed setpoint n_s by X implements a gearbox function. If X=2, for example, rotation speed setpoint n_s will correspond to half the desired rotation speed n of motor **32**, in other words, motor M will run exactly twice as fast as rotation speed setpoint and if X=½, for example, rotation speed setpoint n_s will correspond to twice the rotation speed n, i.e. motor M will rotate at half the value of the rotation speed defined by n_s. This is explained below using a quantitative example.

This step establishes a specific ratio

*n/n* _{—} *s=X* (8)

between rotation speed n and rotation speed setpoint n_s. This also means a fixed ratio, for example

*f* _{—} *s/f=y/z* (1)

between actual frequency and setpoint frequency f_s, as explained in FIG. **1**.

As is directly evident from S**530**, the system deviation could also be calculated differently, e.g. using the equation

*n* _{—} *s−Y*n* (7a)

as indicated at **145**′ in FIG. 7, or using the equation

*A*n* _{—} *s−B*n* (7b)

or using a suitable mathematical function, for example ln(n_s), or a time function, e.g.

*n* _{—} *s**sin *t*)−*n* (7c)

in which case the rotation speed would oscillate periodically between the positive rotation speed (n_s) and the negative rotation speed−(n_s). This requires, of course, a motor that can run in both rotation directions. A motor **32**″ of this kind is depicted as an example in FIG. **29**. Most electronically commutated motors run in both rotation directions and are suitable for such applications.

It is also possible to introduce a gearbox factor by, for example, counting only every second “event” to obtain setpoint frequency f_s; and the same applies analogously to actual frequency f. Since numerical values are being compared to one another, any kind of known mathematical manipulation of those numerical values is possible, particular advantages always being yielded in individual cases.

Several further possibilities for embodying an “electronic gearbox”, will be presented and explained below.

The multiplication of n_s by X can be performed, for example, as a fixed-point multiplication. In fixed-point multiplication, variable X is assumed to have a decimal point at a fixed location, so that the bits to the right of the decimal point correspond to multiplication by ½, ¼, etc. The advantage of fixed-point multiplication is that places after the decimal point are not lost.

A frequency f_s corresponding to a rotation speed setpoint of 3000 rpm is delivered from setpoint generator **20** (FIG. **1**). Motor **32** needs, however, to run with a gearbox factor X that equals 0.5, i.e. at 1500 rpm.

In part **143** in FIG. 7 (corresponding to the flow charts in FIGS. **14** and **15**), a rotation speed setpoint n_s of 3000.00 rpm is calculated from frequency f_s. The number 300,000 (corresponding to 493E0 in hexadecimal) is used internally in the computer because of its higher accuracy. This number is multiplied by the gearbox factor X=0.5, and the hexadecimal value 249F0 is obtained as setpoint X*n_s.

Motor **32** is rotating at the moment at 1499.99 rpm. The number 149,999 (as the hexadecimal number 249EF) is used in the computer because of its higher accuracy. This corresponds in FIG. 7 to the actual rotation speed n.

System deviation RGL_DIFF is then calculated in system deviation calculator **151** in S**530** (FIG. **18**), i.e.

*n* _{—} *s*X−n*=249F0−249EF=1 (decimal)

(the value 1 is indicated in the decimal system to improve comprehension). Since the values for X*n_s and n had, in this example, previously been multiplied by 100, this value must be divided by 100 again; i.e. the actual value of the system deviation is 1/100=0.01 rpm.

This numerical value is further processed in S**532** (FIG. 18) in the PI controller; and since the rotation speed is slightly too low, variable RGL_VAL is increased by the PI controller to bring the rotation speed to exactly 1500 rpm. Steps S**534** through S**540** hold variable RGL_VAL within the permissible limits 0 and RGL_MAX.

Thus, although a setpoint of 3000 rpm was defined as frequency f_s, the motor is controlled to 1500 rpm because a “gearbox factor” X of 0.5 is set. A different gearbox factor, e.g. 0.333, could also be set in similar fashion, and the motor would then be regulated to 1000 rpm.

It is also apparent from this example that one could just as easily leave the value for n_s unchanged, and instead multiply the value for n by 2 (in this example). The value for the system deviation would then be twice as great, but the control process would proceed in the same way.

The ratio n/n_s can also, additionally or alternatively, be influenced in the context of frequency measurement and rotation speed calculation by, for example, selecting different variables h (S**372** in FIG. 15) and h_s (S**472** in FIG. **16**).

Taking into account the value of MOD_f in the measurement of actual frequency f (S**324** in FIG. 13) and the value of MOD_f_s in the measurement of setpoint frequency f_s (S**424** in FIG. 14) can also bring about a change in the ratio between frequencies f and f_s and thus also between rotation speeds n and n_s.

The point at which the desired ratio between rotation speeds n and n_s and between frequencies f and f_s is established is not significant for the present invention. The ratio must, however, be established at a suitable point.

S**352** of FIG. 18 depicts a digital PI controller.

Proportional component RGL_PROP is calculated by multiplying system deviation RGL_DIFF by proportional factor RGL_P.

The new integral component is calculated by adding the previous integral component to system deviation RGL DIFF multiplied by integral factor RGL_I. Integral component RGL_INT preferably has sufficient memory available to it that no system deviation information is lost. Control output RGL_VAL is determined from the sum of proportional component RGL_PROP and integral component RGL_INT.

A range check of control output RGL_VAL is performed in steps S**534** through S**540**.

If control output RGL_VAL is less than zero in S**534**, it is then set is to zero in S**536**.

If control output RGL_VAL is greater than the maximum permissible value RGL_MAX in S**538**, it is set to RGL_MAX in S**540**. The purpose of this is to limit control output RGL_VAL to maximum value RGL_MAX during acceleration of a motor, when large system deviations can exist.

If the value of RGL_VAL lies within a permissible range, it is used unchanged.

In S**542**, register PWM_SW of the PWM generator inside the μC is set to control output RGL_VAL, and PWM signal PWM_SW is outputted as described in FIG. **5**.

Controller function S**628** is thus complete, and function register bit FCT_RGL is reset in S**544**.

Execution then branches back to the beginning S**602** of the function manager (FIG. **8**).

Instead of the PI controller just described, it is also possible to use, for example, a PID controller or a different controller. Digital controllers in which all the bits of system deviation RGL_DIFF are taken into account (as guaranteed here by integral component RGL_INT) are advantageous. Controller factors RGL_P and RGL_I can be set separately in order to adapt the controller optimally to its particular task.

FIG. 19 shows a state diagram which summarizes in simple and comprehensible fashion the complex functional sequences of the previous Figures already described. Table 2 below provides the necessary explanations for this state diagram, and is largely self-explanatory (WDT means “watchdog timer”).

Transition | Result | Action | From . . . to |

T20 | Hardware reset | Branch to program | −> M |

address 00h | |||

T21 | Watchdog timer | Branch to program | −> M |

reset | address 00h | ||

T22 | Immediate state | No action | M −> N |

change with no | |||

event | |||

T23 | Immediate state | Initialization. (Optional) | N −> O |

change with no | retrieval of parameters | ||

event | from EEPROM 80 | ||

T24 | Calculation of actual | Perform calculation of | O −> O |

value started | actual value. Reset | ||

counter INT_CALC_f. | |||

Stop and inhibit | |||

calculation of | |||

actual value. | |||

T25 | Calculation of | Perform calculation of | O −> O |

setpoint started | setpoint. Reset counter | ||

INT_CALC_f_s. | |||

Stop and inhibit | |||

calculation of | |||

setpoint. | |||

T26 | Calculation of | Start controller | O −> O |

setpoint and actual | |||

value stopped. | |||

Controller enabled. | |||

T27 | Controller started | S530 (X * n_s). | O −> O |

Controller RGL | |||

(FIG. 18). | |||

S542 (setpoint output), | |||

S544 (stop and inhibit | |||

controller). | |||

In the 0 (idle) state, the program is ready for action and performs various actions as required. At T**24**, for example, calculation of the actual frequency value is performed, counter INT_CALC_f is reset, and the actual value calculation is then inhibited until a new measurement has been performed. At transition T**25**, the same actions are performed for the setpoint.

At T**26** the calculations of the setpoint and actual value are stopped, and controller RGL (FIG. 1) is started. The controller is then started at T**27**. In step S**530**, gearbox ratio X is taken into account. The calculations in the PI controller are performed, the control output is outputted in S**542**, and in S**544** the controller is stopped and temporarily inhibited until new values are available after the next measurement.

States M and N usually are passed through only upon startup, since a hardware reset takes place at that time. If the watchdog (not depicted) detects any irregular behavior of μC **23**, actions T**21**, T**22**, and T**23** are performed in order to return μC **23** to its normal operating state **0**.

FIG. 20 shows a state diagram for a controller in which a rotation speed setpoint n_s=**0** can also be set.

Function RGL_ON S**624** of FIG. 17 waits to start controller function RGL S**628** until a value is present both for rotation speed setpoint n_s and for rotation speed n.

This creates difficulties with motors that need also to be controlled down to a rotation speed n=0, since no interrupts are triggered if signals f or f_s have a frequency of zero, because no edges of signals f Aft and f_s are present.

The controller shown in FIG. 21 allows control to a rotation speed of zero, and therefore represents a preferred development.

The state diagram contains six states S**10** to S**15**, and nine transitions T**10** to T**18**.

In Table 3 below, transitions T**10** to T**18** are described along with their events and actions. This table, like Tables 1 and 2, is comprehensible in and of itself.

Transition | Event | Action |

T10 | Controller has been started by | RGL_ON is started; |

TIMER0 interrupt | branch to S11 | |

T11 | Rotation speed setpoint n_s is | Branch to S12 |

present | ||

T12 | Time-out time for measurement of | n_s :=0; branch to S12 |

n_s has been exceeded | ||

T13 | Rotation speed n is present | Start controller; |

calculate control | ||

output; branch to S13 | ||

T14 | Time-out time for measurement of | n :=0; start controller; |

n has been exceeded, and | calculate control | |

n_s = 0 | output; branch to S13 | |

T15 | Instantaneous | Output control output; |

branch to S14 | ||

T16 | Instantaneous | Terminate controller; |

branch to S10 | ||

T17 | Time-out time for measurement of | Output maximum control |

n has been exceeded, and | output; branch to S15 | |

n_s < > 0 | ||

T18 | Instantaneous | Terminate RGL_ON; |

branch to S10 | ||

In state S**10**, execution waits for the controller to start.

When the controller is started, for example by means of routine TIMER**0** Interrupt S**639** of FIG. 12, execution branches to state S**11** and then waits for rotation speed setpoint n_s.

If a value for rotation speed setpoint n_s is present, transition T**11** to state S**12** takes place.

If, however, a time-out time has been exceeded in S**11** and no value for rotation speed setpoint n_s is present, transition T**2** to state S**12** (in which transition T**12** rotation speed setpoint n_s is set to zero) then takes place.

In state S**12**, execution waits for rotation speed n of motor M. If a value for n is present, transition T**13** to S**13** takes place, controller function RGL S**628** is started, and a new control output RGL_VAL is calculated.

From state S**13**, an instantaneous transition T**15** to S**14** takes place, and the calculated control output RGL_VAL is outputted.

From state S**14**, an instantaneous transition T**16** to S**10** takes place, and execution waits for the new start.

If a time-out time is exceeded in state S**12**, the motor has a rotation speed n=0.

A distinction is made between two cases when n=0. If rotation speed setpoint n_s is also equal to zero, transition T**14** to S**13** takes place and controller RGL S**628** calculates a new control output RGL_VAL.

If, however, rotation speed n=0 and rotation speed setpoint n_s is not equal to zero, then either motor M is jammed or it needs to be started. A transition T**17** to S**15** takes place, and a maximum control output is outputted.

From state S**15**, an instantaneous transition T**18** to state S**10** takes place, and execution waits for the next start.

FIG. 21 shows a flow chart for a routine RGL_ON**2** S**624** adapted to FIG. 20, i.e. for the case in which n_s=0 also needs to be taken into consideration.

S**500** checks whether rotation speed setpoint calculation routine CALC_n_s S**620** (FIG. 16) has been executed, i.e. whether a rotation speed setpoint n_s is present.

If Yes, execution then branches to S**506**.

If No, S**502** then checks whether a time-out time t_TO_s has been exceeded since the last measurement. This is done by calculating the difference between instant t_END_f_s of the last measurement (cf. FIG. 14) and the present instant of timer TIMER**1**, and comparing it to time-out time t_TO_s.

If time-out time t_TO_s has not yet been exceeded, execution branches to the beginning S**602** of the function manager (FIG. **8**), and waits for ; rotation speed setpoint n_s.

If time-out time t_TO_s has been exceeded, however, rotation speed setpoint n_s is then set to zero in S**504**. Instant t_END_f_s of the last measurement is furthermore set to the instantaneous value t_TIMER**1** of TIMER**1**, so that TIMER**1** does not exceed the value t_END_f_s. Execution then branches to S**506**.

S**506**, analogously to S**500**, checks whether a value for rotation speed n is present.

If Yes, then controller function RGL S**628** (FIG. 18) is requested in S**514** by setting function register bit FCT_RGL to 1, and routine RGL_ON**2** is terminated by resetting FCT RGL_ON to zero.

If a value for rotation speed n is not present in S**506**, S**508** then checks, by analogy with S**502**, as to whether time-out time t_TO has been exceeded since the last measurement of rotation speed n at instant t_END_f.

If No, execution then branches to S**602** (FIG. **8**), and continues to wait for a value for rotation speed n.

If time-out time t_TO has been exceeded, S**510** checks whether rotation speed setpoint n_s=0.

If Yes, execution then branches to S**514**, and controller function RGL S**628** is called with values n=0 and n_s=0.

If No, then either motor M is jammed, or it needs to be started at that time. Register PWM_SW of the PWM generator of μC **23** is therefore set in S**512** to the maximum control output RGL_MAX. The value t_END_f is set, by analogy with S**504**, to the instantaneous timer value t_TIMER**1** in order to prevent any overflow; and routine RGL_ON**2** S**624** is terminated by setting FCT_RGL_ON to zero and branching to S**602**.

This variant does not require any further modifications to be made to controller function RGL S**628**.

Time-out times t_TO_s and t_TO must be selected in accordance with the requirements of the controller and the motor. For example, a relatively short time-out time can be used to ensure that the motor is shut off below a defined minimum rotation speed. Many motors, for example gasoline engines, are difficult to regulate at low speeds since they then tend to oscillate, and it may be desirable in such cases not to allow these rotation speed ranges.

A typical value for t_TO is 100 ms, corresponding to a motor rotation speed of approx. 50 rpm. A value of 1000 ms would correspond to a rotation speed of approx. 5 rpm. In an electric motor, however, such a high value can result in thermal overload of the output-stage transistors (transistors **740**, **744** in FIG. **29**).

All the variables explained so far can be defined by the manufacturer; in other words, the manufacturer “parameterizes” the motor. The variables can be present in a nonvolatile memory, e.g. in a ROM, flash ROM, or EEPROM **80** of FIG. 3; or they can be set, for example, using DIP switches. When the motor is started, they are then loaded, for example in step INIT S**602** (FIG. **8**), into the RAM of μC **23**.

The variables that are used can also, if applicable, be modified via bus B (FIG. **3**). By way of this external bus B, the variables in EEPROM **80** can be modified if applicable. Alternatively, EEPROM **80** can be programmed by the manufacturer before it is installed. Other variables can also be programmed, for example proportional factor RGL_P of the controller, integral factor RGL_I, and the overall gain of the controller (FIG. **18**). When different motors are used, this can be very important in terms of achieving optimum drive results.

The ability to influence variables MOD_f, MOD_f_s, and X is particularly important. With MOD_f and MOD_f_s it is possible to adjust the controller to different numbers of poles in the rotors used, and to different types of setpoint frequency generators **20**. If f_s were generated, for example, by two-pole rotor **732** and Hall generator **61** of FIG. 29, MOD_f_s would then be set to 2 (or optionally also to 4) in order to obtain first-class control process results.

By adapting the parameters to the type of motor and setpoint generator being used, it is thus possible to use the same program for different motor types. The use of the same program for different motor types eliminates production and development costs, and the manufacturer can react very flexibly to customer needs. Distributors or preferred customers can also be permitted to program EEPROM **80** themselves, for example in the context of experiments to optimize a drive system. A password function can prevent unauthorized programming by users.

Parameterization of gearbox factor X allows the same setpoint frequency generator **20** to be used for several motors which must run with a fixed rotation speed ratio among them, although the rotation speed can differ from one motor to another. Gearbox factor X makes possible, for example, continuous tensioning during transport of a material web (e.g. 4 plastic films or textiles), if a gearbox factor X=1000 is selected for a first motor and a gearbox factor X=1001 for a second motor farther ahead in the direction of motion. This causes the second motor to run very slightly faster, thus causing tensioning of the web being transported.

Regulation by means of setpoint frequency f_s becomes more dynamic the higher the value of that frequency. With a higher setpoint frequency, however, μC **23** also experiences a greater calculation operation load. A ratio between setpoint frequency f_s and actual frequency f of f_s:f≧5:1 has proven advantageous for motors that must react quickly to changes in setpoint frequency. “Frequency” here is understood to mean the number of events per unit time, for example the number of edges **110** per second in the case of a Hall signal (FIG. **4**).

FIG. 26 shows an example of the use of three motors according to the present invention. A setpoint frequency f_s is delivered from a frequency generator **180** via a line **187** to three motors **181**, **183** and **185** according to the present invention. The rotor of motor **181** has two poles, that of motor **183** has four poles, and that of motor **185** has six poles. Different motors are necessary, for example, if motors with different power levels are required at various locations.

In this exemplary embodiment, all three motors are intended to run at the same rotation speed defined by the setpoint frequency. For that purpose, for example, gearbox factors X(**181**) of motor **181**, x(**183**) of motor **183**, and X(**185**) of motor **183** are set to X(**181**)=1, X(**183**)=2, and X(**185**)=3.

FIG. 27 schematically shows a photocopier unit having three motors M**1**, M**2**, and M**3** according to the present invention, which receive a defined frequency setpoint f_s via a line **187** from a frequency generator **180**. If motor M**2**, which, for example, drives a roller, requires a rotation speed different from motors M**1** and M**3**, it can be set via a gearbox factor X.

It is advantageous for a unit of this kind if a controller as shown in FIG. 20, with which the rotation speed of the motors can be regulated to zero by means of setpoint frequency f_s, is used.

FIG. 28 shows a further exemplary embodiment having three motors M**1**, M**2**, and M**3**. Motor M**1** emits a so-called tacho signal. A tacho signal can be generated, for example, by outputting the signal of rotor position sensor **61**. Using the tacho signal, further motors M**2**, M**3** according to the present invention can be regulated at a fixed ratio to the rotation speed of motor M**1**. The result, even without any special frequency generator, is that the three motors run at a fixed rotation speed ratio to one another, since motor M**1** serves as a frequency generator.

In the context of the invention, therefore, a setpoint datum that is contained in the frequency of a setpoint frequency signal is delivered to a μC. A motor for which that setpoint is determined in turn sends back a frequency signal which contains as datum the actual rotation speed of that motor. This frequency signal can come, for example, from a tachogenerator, a resolver, a sensor within the motor (e.g. a Hall generator for controlling commutation of the motor), or from other types of sensors.

The setpoint frequency and actual frequency are sensed, continuously and approximately synchronously, in the μC and converted into numerical values that are proportional to rotation speed. These numerical values can then be manipulated with defined parameters, usually by multiplication or division. (Said parameters can be stored, for example, in an EEPROM.) What is obtained as a result is, for example, a multiple of the sensed setpoint frequency or a fraction of the sensed setpoint frequency, or a multiple of the sensed actual frequency or a fraction of the sensed actual frequency. These manipulated values are delivered to a rotation speed controller, and a gearbox function can thereby be implemented. In order to adapt or vary the control properties, it is moreover very easy to modify control parameters that influence the control behavior of the system.

The manipulated values are compared to one another in the rotation speed controller, the system deviation is determined from them and processed in a PI controller or a PID controller (as discussed in detail in S**532** with reference to an example), and the control output generated in the controller is written, for example, into a PWM register. A corresponding PWM signal is outputted as the control output and, in the exemplary embodiment described, converted with an RC filter **65**, **67** into an analog DC voltage signal. The latter is delivered to an adjusting member which controls energy delivery to the motor. The motor in turn sends a defined number of pulses or other signals (“events”) back to the μC, and these provide the controller with exact digital information as to the present rotation speed of the motor.

Many modifications are, of course, possible in the context of the present invention. The gearbox factor X can be set at many points, as explained, and the actual frequency (corresponding to the actual rotation speed) can be generated in many different ways.

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Classifications

U.S. Classification | 318/268, 318/799, 318/798, 318/779, 318/807 |

International Classification | G01P3/489, H02P7/288, H02P5/68, G01D5/14 |

Cooperative Classification | H02P5/68, H02P7/288, G01D5/145, G01P3/489 |

European Classification | G01P3/489, G01D5/14B1, H02P5/68, H02P7/288 |

Legal Events

Date | Code | Event | Description |
---|---|---|---|

Nov 1, 2001 | AS | Assignment | Owner name: PAPST MOTOREN GMBH & CO. KG, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:DIETERLE, ROLAND;HAHN, ALEXANDER;RAPPENECKER, HERMANN;REEL/FRAME:012521/0441 Effective date: 20011022 |

Jul 10, 2007 | AS | Assignment | Owner name: EBM-PAPST ST GEORGEN GMBH & CO. KG, GERMANY Free format text: CHANGE OF NAME;ASSIGNOR:PAPST-MOTOREN GMBH & CO. KG;REEL/FRAME:019544/0541 Effective date: 20031020 |

Aug 21, 2007 | CC | Certificate of correction | |

Feb 13, 2008 | FPAY | Fee payment | Year of fee payment: 4 |

Jul 30, 2012 | REMI | Maintenance fee reminder mailed | |

Dec 13, 2012 | FPAY | Fee payment | Year of fee payment: 8 |

Dec 13, 2012 | SULP | Surcharge for late payment | Year of fee payment: 7 |

Jul 22, 2016 | REMI | Maintenance fee reminder mailed | |

Dec 14, 2016 | LAPS | Lapse for failure to pay maintenance fees | |

Jan 31, 2017 | FP | Expired due to failure to pay maintenance fee | Effective date: 20161214 |

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